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Microstructure, mechanical, in vitro and in vivo behavior of extruded Mg alloys with varying Zn/Gd ratios, Mg-2Gd-2Zn-0.5Zr (Zn/Gd = 1), Mg-2Gd-6Zn-0.5Zr (Zn/Gd = 3), and Mg-10Gd-1Zn-0.5Zr (Zn/Gd = 0.1) were investigated. The results revealed that the major secondary phases such as W (Mg3Zn3Gd2), (Mg,Zn)3Gd, LPSO (Long period stacking order) and I (Mg3Zn6Gd) phase in alloys depended on Zn/Gd ratio. These second phases influenced the mechanical as well as biological characteristics of the alloys. Among studied alloys, Mg-10Gd-1Zn-0.5Zr alloy showed the highest yield strength and tensile strength of 270 (±9.29) and 330 MPa (±15.8), respectively, with a reasonably good elongation of 12% (±2.36). The presence of Gd2O3 in the degradation film of Mg-10Gd-1Zn-0.5Zr enhanced the resistance offered by the film, which resulted in its lowest biodegradation, better viability, and cell proliferation under in vitro condition. The short term (subcutaneous implantation in rats for 1 month) in vivo studies showed that the alloy Mg-10Gd-1Zn-0.5Zr degraded at a rate of 0.35 mm/y (±0.02) and did not induce any toxicity to the vital organs.

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BACKGROUND: Extrathyroid implantation or dissemination of thyroid tissue secondary to a thyroid procedure is rare. Most of these belonged to thyroid carcinoma with metastatic potential and uncommon for benign pathologies. METHODS: We report the case of a 31-year-old female who was identified to have multiple subcutaneous implantation of thyroid tissue 5 years after transoral endoscopic thyroidectomy vestibular approach. A comprehensive literature search on implantation of thyroid tissue secondary to thyroid procedures was performed. RESULTS: Accidental tearing of the capsule during previous surgery may lead to the subcutaneous implantation. Through literature review, a total 29 articles with 47 patients were identified. 33.3% were benign lesions, and implantation was mostly secondary to fine needle aspiration biopsy (46.5%). CONCLUSIONS: Subcutaneous or port site implantation after endoscopic thyroid surgery may occur in benign thyroid pathologies and therefore, oncologic principles must be strictly followed during surgery regardless of its histopathological nature.

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Biomaterials that can improve the healing of articular cartilage lesions are needed. To address this unmet need, we developed novel 3D printed silica/poly(tetrahydrofuran)/poly(ε-caprolactone) (SiO2/PTHF/PCL-diCOOH) hybrid scaffolds. Our aim was to carry out essential studies to advance this medical device towards functional validation in pre-clinical trials. First, we show that the chemical composition, microarchitecture and mechanical properties of these scaffolds were not affected by sterilisation with gamma irradiation. To evaluate the systemic and local immunogenic reactivity of the sterilised 3D printed hybrid scaffolds, they were implanted subcutaneously into Balb/c mice. The scaffolds did not trigger a systemic inflammatory response over one week of implantation. The interaction between the host immune system and the implanted scaffold elicited a local physiological reaction with infiltration of mononuclear cells without any signs of a chronic inflammatory response. Then, we investigated how these 3D printed hybrid scaffolds direct chondrogenesis in vitro. Human bone marrow-derived mesenchymal stem/stromal cells (hBM-MSCs) seeded within the 3D printed hybrid scaffolds were cultured under normoxic or hypoxic conditions, with or without chondrogenic supplements. Chondrogenic differentiation assessed by both gene expression and protein production analyses showed that 3D printed hybrid scaffolds support hBM-MSC chondrogenesis. Articular cartilage-specific extracellular matrix deposition within these scaffolds was enhanced under hypoxic conditions (1.7 or 3.7 fold increase in the median of aggrecan production in basal or chondrogenic differentiation media). Our findings show that 3D printed SiO2/PTHF/PCL-diCOOH hybrid scaffolds have the potential to support the regeneration of cartilage tissue.

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Developing biocompatible, non-fouling and biodegradable hydrogels for blood-contacting devices remains a demanding challenge. Such materials should promote natural healing, prevent clotting, and undergo controlled degradation. This study evaluates the biocompatibility and biodegradation of degradable poly(2-hydroxyethyl methacrylate) (d-pHEMA) hydrogels with or without reinforcement with oxidized few-layer graphene (d-pHEMA/M5ox) in a long term implantation in rats, assessing non-desired side-effects (irritation, chronic toxicity, immune response). Subcutaneous implantation over 6 months revealed degradation of both hydrogels, despite slower for d-pHEMA/M5ox, with degradation products found in intracellular vesicles. No inflammation nor infection at implantation areas were observed, and no histopathological findings were detected in parenchymal organs. Immunohistochemistry confirmed d-pHEMA and d-pHEMA/M5ox highly anti-adhesiveness. Gene expression of macrophages markers revealed presence of both M1 and M2 macrophages at all timepoints. M1/M2 profile after 6 months reveals an anti-inflammatory environment, suggesting no chronic inflammation, as also demonstrated by cytokines (IL-α, TNF-α and IL-10) analysis. Overall, modification of pHEMA towards a degradable material was successfully achieved without evoking a loss of its inherent properties, specially its anti-adhesiveness and biocompatibility. Therefore, these hydrogels hold potential as blank-slate for further modifications that promote cellular adhesion/proliferation for tissue engineering applications, namely for designing blood contacting devices with different load bearing requirements. STATEMENT OF SIGNIFICANCE: Biocompatibility, tunable biodegradation kinetics, and suitable immune response with lack of chronic toxicity and irritation, are key features in degradable blood contact devices that demand long-term exposure. We herein evaluate the 6-month in vivo performance of a degradable and hemocompatible anti-adhesive hydrogel based in pHEMA, and its mechanically reinforced formulation with few-layer graphene oxide. This subcutaneous implantation in a rat model, shows gradual degradation with progressive changes in material morphology, and no evidence of local inflammation in surrounding tissue, neither signs of inflammation or adverse reactions in systemic organs, suggesting biocompatibility of degradation products. Such hydrogels exhibit great potential as a blank slate for tissue engineering applications, including for blood contact, where cues for specific cells can be incorporated.

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Immunoregulatory and vascularized microenvironments play an important role in bone regeneration; however, the precise regulation for vascularization and inflammatory reactions remains elusive during bone repair. In this study, by means of subcutaneous preimplantation, we successfully constructed demineralized bone matrix (DBM) grafts with immunoregulatory and vascularized microenvironments. According to the current results, at the early time points (days 1 and 3), subcutaneously implanted DBM grafts recruited a large number of pro-inflammatory M1 macrophages with positive expression of CD68 and iNOS, while at the later time points (days 7 and 14), these inflammatory cells gradually subsided, accompanying increased presence of anti-inflammatory M2 macrophages with positive expression of CD206 and Arg-1, indicating a gradually enhanced anti-inflammatory microenvironment. At the same time, the gradually increased angiogenesis was observed in the DBM grafts with implantation time. In addition, the positive cells of CD105, CD73, and CD90 were observed in the inner region of the DBM grafts, implying the homing of mesenchymal stem cells. The repair results of cranial bone defects in a rat model further confirmed that the subcutaneous DBM xenografts at 7 days significantly improved bone regeneration. In summary, we developed a simple and novel strategy for bone regeneration mediated by anti-inflammatory microenvironment, prevascularization, and endogenous stem cell homing.

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Background: There is a strong interest in designing new scaffolds for their potential application in tissue engineering and regenerative medicine. The incorporation of functionalization molecules can lead to the enhancement of scaffold properties, resulting in variations in scaffold compatibility. Therefore, the efficacy of the therapy could be compromised by the foreign body reaction triggered after implantation. Methods: In this study, the biocompatibilities of three scaffolds made from an alginate-chitosan combination and functionalized with gold nanoparticles (AuNp) and alginate-coated gold nanoparticles (AuNp + Alg) were evaluated in a subcutaneous implantation model in Wistar rats. Scaffolds and surrounding tissue were collected at 4-, 7- and 25-day postimplantation and processed for histological analysis and quantification of the expression of genes involved in angiogenesis, macrophage profile, and proinflammatory (IL-1ß and TNFα) and anti-inflammatory (IL-4 and IL-10) cytokines. Results: Histological analysis showed a characteristic foreign body response that resolved 25 days postimplantation. The intensity of the reaction assessed through capsule thickness was similar among groups. Functionalizing the device with AuNp and AuNp + Alg decreased the expression of markers associated with cell death by apoptosis and polymorphonuclear leukocyte recruitment, suggesting increased compatibility with the host tissue. Similarly, the formation of many foreign body giant cells was prevented. Finally, an increased detection of alpha smooth muscle actin was observed, showing the angiogenic properties of the elaborated scaffolds. Conclusion: Our results show that the proposed scaffolds have improved biocompatibility and exhibit promising potential as biomaterials for elaborating tissue engineering constructs.

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Background: Subcutaneous implantation of thyroid tissue after thyroidectomy is a rare occurrence involving both benign and malignant thyroid tissue. Clinically, subcutaneous implantation of thyroid tissue can be challenging to diagnose. We present two cases of subcutaneous implantation of thyroid tissue following thyroidectomy and discuss the differential diagnosis, clinicopathological characteristics, and the possible mechanism of implantation. Case Description: A 35-year-old woman (age in 2009) who underwent total thyroidectomy in 2009 whose histopathological examination revealed a nodular hyperplasia and lymphocytic thyroiditis complained of palpable mass in her neck 10 years after operation and underwent excision. Follicular adenoma was confirmed in histopathological results. A 58-year-old woman (age in 2010) who underwent lobectomy in 2010 for nodular hyperplasia had a 6 cm sized huge mass in her anterior neck 9 years after operation. Anterior neck mass excision was done and poorly differentiated carcinoma was confirmed in histopathological results. The patient showed no sign of recurrence after 3 years follow-up. Conclusions: Subcutaneous implantation of benign thyroid tissue or thyroid cancer can occur after thyroidectomy. Minimizing the likelihood of subcutaneous implantation requires careful consideration of various factors at every stage of the surgical procedure. Surgeons should be aware of this potential long-term complication that can occur in both conventional thyroidectomy and remote access surgery, effectively communicate and provide appropriate guidance to their patients, and try to avoid seeding of both malignant and benign thyroid tissue.

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Since the heart pumps out the blood through the excitation-contraction coupling, simultaneous monitoring of the electrical and mechanical characteristics is beneficial for comprehensive diagnosis of cardiac disorders. Currently, these characteristics are monitored separately with electrocardiogram (ECG) and medical imaging techniques. This work presents a fully implantable device named mechano-electrocardiogram (MECG) sensor that can measure mechanocardiogram (MCG) and ECG together. The key to the success is fabrication of permeable electrodes on a single low-modulus porous nanofiber mat, which helps immediate adhesion of the sensor on the tissue. A strain-insensitive electrode is used as the ECG electrode and a strain-sensitive electrode is used for MCG. The MECG device is implanted subcutaneously in the skin above the heart of the rat. Through a vasopressor (phenylephrine) injection test, the MECG signals indicate that the MCG amplitude is related with blood pressure and the ECG peak interval is more related with heart rate. These results confirm that the MECG device is clinically meaningful for continuous and comprehensive monitoring of the electrical and mechanical characteristics of the heart.

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Calcium salt precipitation induced by intracanal medicaments contributes to the formation of apical hard tissue during apexification. This study compared the calcium salt-forming ability of a new calcium silicate-based intracanal medicament (Bio-C Temp) with that of two commercial calcium hydroxide pastes (Calcipex Plane II and Vitapex) in a rat subcutaneous implantation model. Polytetrafluoroethylene tubes containing each of the three materials were subcutaneously implanted in 4-week-old male Wistar rats. After 28 days, the composition and amount of calcium salts formed at the material-tissue interface were assessed using micro-Raman spectroscopy, X-ray diffraction, and elemental mapping. The tested materials produced white precipitates that had Raman spectra with peaks corresponding to hydroxyapatite and calcite. X-ray diffraction detected hydroxyapatite formation on Calcipex Plane II and Vitapex implants, as well as calcite formation on all three materials. Elemental mapping revealed that Bio-C Temp generated significantly smaller calcium- and phosphorus-rich calcified regions within the subcutaneous connective tissue than Vitapex. These results indicate that Bio-C Temp produced less calcium salt in rat subcutaneous tissue than Vitapex, although all materials formed hydroxyapatite and calcite in rat subcutaneous tissue. Bio-C Temp could be less effective than Vitapex in promoting apical hard tissue formation during apexification.

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Hydroxyapatite formation on endodontic hydraulic calcium silicate cements (HCSCs) plays a significant role in sealing the root canal system and elevating the hard-tissue inductivity of the materials. This study evaluated the in vivo apatite-forming ability of 13 new-generation HCSCs using an original HCSC (white ProRoot MTA: PR) as a positive control. The HCSCs were loaded into polytetrafluoroethylene tubes and implanted in the subcutaneous tissue of 4-week-old male Wistar rats. At 28 days after implantation, hydroxyapatite formation on the HCSC implants was assessed with micro-Raman spectroscopy, surface ultrastructural and elemental characterization, and elemental mapping of the material-tissue interface. Seven new-generation HCSCs and PR had a Raman band for hydroxyapatite (v1 PO43- band at 960 cm-1) and hydroxyapatite-like calcium-phosphorus-rich spherical precipitates on the surfaces. The other six HCSCs with neither the hydroxyapatite Raman band nor hydroxyapatite-like spherical precipitates did not show calcium-phosphorus-rich hydroxyapatite-layer-like regions in the elemental mapping. These results indicated that 6 of the 13 new-generation HCSCs possessed little or no ability to produce hydroxyapatite in vivo, unlike PR. The weak in vivo apatite-forming ability of the six HCSCs may have a negative impact on their clinical performance.

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As a Natural decellularized extracellular matrix, osteochondral tissue is the best scaffold for the restoration of osteoarthritis defects. Bioscaffolds have the most similarly innate properties like biomechanical properties and the preserved connection of the bone-to-cartilage border. Although, their compacity and low porosity particularly, are proven to be difficulties of decellularization and cell penetration. This study aims to develop a new bioscaffold of decellularized osteochondral tissue (DOT) that is recellularized by bone marrow-derived mesenchymal stem cells (BM-MSCs), as a biphasic allograft, which preserved the interface between the cartilage section and subchondral bone of the joint. Whole osteochondral tissues of rabbit knee joints were sheeted in cartilaginous parts in 200-250 µm sections while connected to the subchondral bone and then fully decellularized. The BM-MSCs were seeded on the scaffolds in vitro; some constructs were subcutaneously implanted into the back of the rabbit. The cell penetration, differentiation to bone and cartilage, viability, and cell proliferation in vitro and in vivo were evaluated by qPCR, histological staining, MTT assay, and immunohistochemistry. DNA content analysis and SEM assessments confirmed the decellularization of the bioscaffold. Then, histological and SEM evaluations indicated that the cells could successfully penetrate the bone and cartilage lacunas in implanted grafts. MTT assay confirmed cell proliferation. Prominently, gene expression analysis showed that seeded cells differentiated into osteoblasts and chondrocytes in both bone and cartilage sections. More importantly, seeded cells on the bioscaffold started ECM secretion. Our results indicate that cartilage-to-bone border integrity was largely preserved. Additionally, ECM-sheeted DOT could be employed as a useful scaffold for promoting the regeneration of osteochondral defects.

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Gutta-percha points and root canal sealers have been used for decades in endodontics for root canal obturation. With techniques such as single cone methods, the amount of sealer is larger, making their properties more critical. However, relatively few reports have comprehensively evaluated their biological effects. To this end, we evaluated three types of sealers, zinc oxide-fatty acid-, bio-glass- and methacrylate resin-containing sealers were considered. Their biological effects were evaluated using a rat subcutaneous implantation model. Each sealer was loaded inside a Teflon tube and implanted subcutaneously in the backs of rats. Inflammatory cells were observed around all samples 7 days after implantation and reduced after 28 days. Our results revealed that all samples were in contact with the subcutaneous tissue surrounding the sealer. Additionally, Ca and P accumulation was observed in only the bio-glass-containing sealer. Furthermore, each of the three sealers exhibited unique immune and inflammatory modulatory effects. In particular, bio-glass and methacrylate resin sealers were found to induce variable gene expression in adjacent subcutaneous tissues related to angiogenesis, wound healing, muscle tissue, and surrounding subcutaneous tissue. These results may help to understand the biological impacts of root canal sealers on surrounding biological tissues, guiding future research and comparisons with new generations of materials.

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Previously, 5% w/v hyaluronic acid-tyramine (HA-TA) and dextran-tyramine (Dex-TA) enzymatically cross-linked hybrid hydrogels were demonstrated to provide a mechanically stable environment, maintain cell viability, and promote cartilaginous-specific matrix deposition in vitro. In this study, 5% w/v hybrid hydrogels were combined with human mesenchymal stem cells (hMSCs), bovine chondrocytes (bCHs), or a combination of both in a 4:1 ratio and subcutaneously implanted in the backs of male and female nude rats to assess the performance of cell-laden hydrogels in tissue formation. Subcutaneous implantation of these biomaterials showed signs of integration of the gels within the host tissue. Histological analysis showed residual fibrotic capsules four weeks after implantation. However, enhanced tissue invasion and some giant cell infiltration were observed in the HA-TA/Dex-TA hydrogels laden with either hMSCs or bCHs but not with the co-culture. Moreover, hMSC-bCH co-cultures showed beneficial interaction with the hydrogels, for instance, in enhanced cell proliferation and matrix deposition. In addition, we provide evidence that host gender has an impact on the performance of bCHs encapsulated in HA-TA/Dex-TA hydrogels. This study revealed that hydrogels laden with different types of cells result in distinct host responses. It can be concluded that 5% w/v hydrogels with a higher concentration of Dex-TA (≥50%) laden with bCH-hMSC co-cultures are adequate for injectable applications and in situ cell delivery in cartilage regeneration approaches.

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A 13-year-old male neutered Cocker Spaniel mixed-breed dog developed a subcutaneous mass 2 years after undergoing surgery to remove a hepatocellular carcinoma. An approximately 4 × 3 cm subcutaneous mass was found on the ventral abdomen at the cranial end of the abdominal incision from the previous surgery. The subcutaneous mass was surgically removed and histopathological examination determined that it was an implantation of the previously excised hepatocellular carcinoma. The diagnosis was confirmed by immunohistochemical labelling with hepatocyte paraffin 1 antibody and pancytokeratin. Based on the location of the subcutaneous mass at the cranial end of the abdominal incision associated with the previous hepatocellular carcinoma resection, it is likely there was iatrogenic metastasis from the primary tumour excision. Subcutaneous iatrogenic metastasis of hepatocellular carcinoma is well recognized in humans but has apparently never been reported in dogs. Clinicians should be aware of this potential surgical complication.

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Protein delivery and release from synthetic scaffold materials are major challenges within the field of bone tissue engineering. In this study, 13-93B1.5 borosilicate bioactive glass (BSG) base paste was 3D printed to produce BSG-based scaffolds with high porosity (59.85 ± 6.04%) and large pore sizes (350-400 µm) for functionalization with a sodium alginate (SA)/calcitonin gene-related peptide (CGRP) hydrogel mixture. SA/CGRP hydrogel was uniformly filled into the interconnected pores of 3D printed BSG constructs to produce BSG-SA/CGRP scaffolds which were subject to bioactivity and biocompatibility analysis. BSG scaffolds filled with SA hydrogel underwent dissolution in simulated body fluid (SBF), resulting in the precipitation of hydroxyapatite (HA) on the borosilicate glass evidenced by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Around 90% of CGRP was released from scaffolds after 7 days of immersion in SBF, reaching a final released concentration of 893.00 ± 63.30 ng/mL. Cellular adhesion, proliferation, and differentiation of human bone marrow mesenchymal stem cells (HBMSCs) cultured with BSG-SA/CGRP scaffolds revealed improved biocompatibility and osteogenic capabilities compared with BSG-SA scaffolds in the absence of CGRP. When subcutaneously implanted in rat models, BSG-SA/CGRP scaffolds induced low localized inflammation without causing bodily harm in vivo. Findings revealed that bioactive glass scaffolds incorporating CGRP met the scaffold requirements for bone regeneration and that the addition of CGRP promoted osteogenic differentiation where it may potentially be utilized for future regenerative applications.

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Unlike conventional monolithic hydrogels with covalent cross-linkage that are typically elastic, colloidal gels assembled by reversibly assembled particles as building blocks have shown fascinating viscoelastic properties. They follow a gel-sol transition upon yielding and recover to the initial state upon the release of the shear force (so-called shear-thinning and self-healing behavior); this makes them an ideal candidate as injectable and moldable biomaterials for tissue regeneration. The immune response provoked by the implantation of the colloidal gels with special viscoelastic and structural features is critical for the successful integration of the implants with the host tissues, which, however, remains little explored. Since macrophages are known as the primary immune cells in determining the inflammatory response against the implants, we herein investigated in vitro macrophage polarization and in vivo inflammatory response induced by gelatin-based colloidal gels as compared to monolithic gels. Specifically, self-healing colloidal gels composed of pure gelatin nanoparticles, or methacrylate gelatin (GelMA) nanoparticles to allow secondary covalent cross-linkage were compared with GelMA bulk hydrogels. We demonstrated that hydrogel's elasticity plays a more dominant role rather than the structural feature in determining in vitro macrophage polarization evidenced by the stiffer gels inducing pro-inflammation M2 macrophage phenotype as compared to soft gels. However, subcutaneous implantation revealed a significantly alleviated immune response characterized by less fibrous capsule formation for the colloidal gels as compared to bulk gels of similar matrix elasticity. We speculated this can be related to the improved permeability of the colloidal gels for cell penetration, thereby leading to less fibrosis. In general, this study provided in-depth insight into the biophysical regulator of hydrogel materials on macrophage behavior and related inflammatory response, which can further direct future implant design and predict biomaterial-host interactions for immunotherapy and regenerative medicine. Impact statement Macrophages response to implanted biomaterials is a highly regulated process that influences device functionality and clinical outcome. Nowadays, the viscoelastic properties of colloidal versus monolithic hydrogels on macrophage phenotype in vitro and the host inflammatory response are not known. Our study found that colloidal hydrogels composed of nanoparticles of gelatin and methacrylate gelatin (GelMA) led to more anti-inflammatory polarization especially on soft colloidal gel (5.9 KPa) compared to bulk GelMA hydrogels. It suggested that macrophage response can be mechanically regulated by the viscoelastic signals of the hydrogels, which could be a promising strategy for the future design and application of novel biomaterials.

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Bio-textiles have aroused attractive attentions in tissue engineering and regenerative medicine, and developing robust, bio-absorbable, and extracellular matrix (ECM) fibril-mimicking nanofibrous textiles is urgently required for the renewal of existing microfibrous textile-based scaffolds and grafts. In this study, an integrated electrospinning system consisting of one nanoyarn-forming unit and one hot stretching unit is reported to fabricate silk fibroin (SF)/poly (L-lactic-acid) (PLLA) nanofibrous yarns (nanoyarns). The hot stretching process is demonstrated to significantly improve the fiber alignment, crystallinity, and mechanical properties of SF/PLLA nanoyarns, compared to the unstretched controls. For instance, the fiber alignment degree of hot stretched 50/50 SF/PLLA nanoyarn has increased by 25%, and the failure strength has increased by 246.5%, compared with the corresponding un-stretched control. Increasing the SF/PLLA mass ratio is found to significantly decrease the crystallinity and mechanical properties, but notably increase the degradation rate and surface hydrophilicity of SF/PLLA nanoyarns. Different SF/PLLA nanoyarns are further meticulously interwoven with warp and weft directions to obtain several nanofibrous woven textiles. The results from in vitro cell characterization and in vivo subcutaneous implantation show that increasing the SF/PLLA mass ratio significantly improves the biological properties and effectively reduces the inflammatory response of nanoyarn-constructed textiles. Overall, this study demonstrates that our SF/PLLA nanoyarns with controllable physical, mechanical and biological performances are fantastic candidates for the designing and development of advanced nanoarchitectured textile tissue scaffolds.

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INTRODUCTION AND IMPORTANCE: Subcutaneous implantation of thyroid tissue is a rare clinical condition that involves the head and neck region and occurs after surgery, diagnostic procedures or cervical trauma. CASE PRESENTATION: A 90-year old woman with two skin nodules on her thyroidectomy scar was hospitalized and treated by two surgical excisions. Histologically, these lesions were two aggregates of cutaneous oncocytic thyroid cells. In the patient's clinical history there was a total thyroidectomy for multinodular goiter, performed 9 years previously and at which a well-encapsulated subcapsular oncocytic adenoma of the left lobe was also incidentally discovered. At 12 months of follow-up, the patient is showed well and her wounds healed. CLINICAL DISCUSSION: Subcutaneous colonization or seeding of thyroid tissue is a rare occurrence reported in the literature for both benign and malignant pathologies; among the malignant ones, the implantation of follicular carcinoma cells is the most frequent. Only in one previous case, to our knowledge, subcutaneous colonization originating from oncocytic thyroid (or Hurthle) cell neoplasms has been described. CONCLUSION: We report an unusual case of double subcutaneous implantation of oncocytic thyroid cells on the cervical scar of an elderly woman, nine years after total thyroidectomy.

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Collagenous biomaterials that are clinically applied in dentistry have dermis-type and membrane-type, both of which are materials for promoting bone and soft tissue formation. The properties of materials supplied with different types could affect their biodegradation periods. The purpose of this study was to characterize five of these products by four different methods: scanning electron microscopy (SEM) observation, thermogravimetry-differential thermal analysis (TG-DTA), 0.01 wt% collagenase dissolution test, and subcutaneous implantation test in vivo. SEM micrographs revealed that both dermis and membranous materials were fibrous and porous. The membranous materials had higher specific derivative thermal gravimetry (DTG) peak temperatures in TG-DTA at around 320 °C, longer collagenase dissolution time ranging from about 300 to 500 min, and more longevity in mice exceeding 9 weeks than the dermis materials. There existed a correlation between the peak temperature in TG-DTA and the collagenase dissolution time. It was considered that higher cross-link degree among collagen fibrils of the membrane-type collagenous materials might account for these phenomena. The experimental protocol and numerical results obtained could be helpful for selection and future development of fibrous collagenous biomaterials in clinical use.

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OBJECTIVE: Bioceramic-containing root canal sealers promote periapical healing via Ca2+ and OH- release and apatite formation on the surface. This study aimed to compare Ca2+ and OH- release and in vivo apatite formation of three bioceramic-containing root canal sealers: EndoSequence BC sealer (Endo-BC), MTA Fillapex (MTA-F), and Nishika Canal Sealer BG (N-BG). MATERIALS AND METHODS: Polytetrafluoroethylene tubes filled with sealers were immersed in distilled water for 6 and 12 h and for 1, 7, 14, and 28 days to measure Ca2+ and OH- release. Additionally, tubes filled with sealers were implanted in the backs of rats for 28 days, and in vivo apatite formation was analyzed using an electron probe microanalyzer. RESULTS: Endo-BC released significantly more Ca2+ than the other sealers at 6 and 12 h and 1 day. Ca2+ release was significantly lower from N-BG than from Endo-BC and MTA-F at 14 and 28 days. OH- release was significantly higher from Endo-BC than from the other sealers throughout the experiment, except at 1 day. OH- release was lower from N-BG than from MTA-F at 6 h and 7 days. Only Endo-BC implants exhibited apatite-like calcium-, phosphorus-, oxygen-, and carbon-rich spherulites and apatite layer-like calcium- and phosphorus-rich, but radiopaque element-free, surface regions. CONCLUSIONS: Ca2+ and OH- release is ranked as follows: Endo-BC > MTA-F > N-BG. Only Endo-BC demonstrated in vivo apatite formation. CLINICAL RELEVANCE: Endo-BC could promote faster periapical healing than MTA-F and N-BG.

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