RESUMEN

Bioactive ions like Mg2+ and Si4+ have been known as promotion factors of tissue regeneration. In the present work, Mg-smectite, consisting of Mg2+ and Si4+ ions, was synthesized by a solution process, and evaluated for the efficiency of the powder on wound healing in rats. White precipitates were obtained by mixing a magnesium chloride hexahydrate solution and a sodium silicate hexahydrate solution at room temperature. The precipitates mixed with a NaOH aqueous solution were subjected to hydrothermal reaction, and finally crystalline Mg-smectite powder was obtained. The crystal and molecular structure of Mg-smectite was identified by X-ray diffractometry (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The synthesized material was determined to be crystalline Mg-smectite. The amount of Mg2+ and Si4+ ions released from Mg-smectite in physiological saline was analyzed by inductively coupled plasma mass spectroscopy (ICP-MS). The total amount of Si4+ ion released from Mg-smectite was greater than that of Mg2+ ion. To evaluate the wound healing effect of Mg-smectite, Mg-smectite powder was applied to a full-thickness surgical wound reaching the subcutaneous tissue in the rat's abdomen. At 1 and 2weeks, skin tissue was collected and subjected to histological analysis. The results for skin regeneration showed no significant difference in wound size between the control and Mg-smectite group. However, it was found that the neovascularization, collagen deposition, and maturation were notedly accelerated by applying Mg-smectite powder in comparison with the control. Mg-smectite can then be hypothesized to stimulate the regeneration of skin tissue by releasing Mg2+ and Si4+ ions. These results suggested that Mg-smectite could offer great potential as a wound dressing material.

Asunto(s)

RESUMEN

Dysfunction of salivary glands leads to several oral health problems, including dental caries, mastication and swallowing dysfunctions and multiple oral infections. Conventional treatments for such condition fell short of providing satisfying therapeutic results. Recent advances in organ regeneration therapy which utilize tissue stem cells to fabricate bioengineered 3D organ buds, have introduced a promising therapeutic tool for full functional organ regeneration. However, finding a sustainable and easily accessible cell source for such approaches is still challenging, especially in case of severely atrophied tissues such as irradiated salivary glands. In response to this, we hypothesized that bone marrow derived mesenchymal stem cells (MSCs) could be used as feeder cells to induce salivary epithelial tissues/cells branching. Indeed, in 2D cultures, MSCs supported branching of embryonic submandibular salivary gland (SMG) epithelium. Interestingly, this enhancing effect was dependent on the initial number of MSC feeder cells. In addition, MSCs supported the self-assembly of SMG epithelial progenitor cells into well-patterned and branched 3D salivary organoids. Therefore, these findings propose MSCs as a valuable candidate cell source for induced SMG epithelial branching, which can potentially be applied in future methods for SMG regeneration approaches.

Asunto(s)

RESUMEN

The importance of macrophages in tissue development and regeneration has been strongly emphasized. However, the specific roles of macrophage colony-stimulating factor (MCSF), the key regulator of macrophage differentiation, in glandular tissue development have been unexplored. Here, we disclose new macrophage-independent roles of MCSF in tissue development. We initially found that MCSF is markedly upregulated at embryonic day (E)13.5, at a stage preceding the colonization of macrophages (at E15.5), in mouse submandibular gland (SMG) tissue. Surprisingly, MCSF-induced branching morphogenesis was based on a direct effect on epithelial cells, as well as indirectly, by modulating the expression of major growth factors of SMG growth, FGF7 and FGF10, via the phosphoinositide 3-kinase (PI3K) pathway. Additionally, given the importance of neurons in SMG organogenesis, we found that MCSF-induced SMG growth was associated with regulation of neurturin expression and neuronal network development during early SMG development in an in vitro organogenesis model as well as in vivo These results indicate that MCSF plays pleiotropic roles and is an important regulator of early SMG morphogenesis.

Asunto(s)

RESUMEN

INTRODUCTION: Salivary gland hypofunction, also known as xerostomia, occurs as a result of radiotherapy for head and neck cancer, autoimmune diseases, or aging. Xerostomia leads to oral health problems and thus affects the quality of life. Biological salivary gland tissue generated in vitro would provide an alternative mode of treatment for this disease. METHODS: To develop a novel method for modulating salivary gland tissue growth in vitro, we prepared a KP24 peptide-immobilized hydrogel sheet, wherein the peptide comprised repeating proline and lysine sequences, and evaluated the effect of this peptide on salivary gland tissue growth. RESULTS: We found that the KP24 peptide has the potential to enhance glandular tissue growth in vitro. This enhancement is associated with neurite outgrowth and increasing neural innervation. CONCLUSION: KP24 peptide modified material would be a promising material for the modulation of salivary gland tissue growth in vitro.

RESUMEN

In vitro fabricated biological tissue would be a valuable tool to screen newly synthesized drugs or understand the tissue development process. Several studies have attempted to fabricate biological tissue in vitro. However, controlling the growth and morphology of the fabricated tissue remains a challenge. Therefore, new techniques are required to modulate tissue growth. RGD (arginine-glycine-aspartic acid), which is an integrin-binding domain of fibronectin, has been found to enhance cell adhesion and survival; it has been used to modify substrates for in vitro cell culture studies or used as tissue engineering scaffolds. In addition, this study shows novel functions of the RGD peptide, which enhances tissue growth and modulates tissue morphology in vitro. When an isolated submandibular gland (SMG) was cultured on an RGD-modified alginate hydrogel sheet, SMG growth including bud expansion and cleft formation was dramatically enhanced. Furthermore, we prepared small RGD-modified alginate beads and placed them on the growing SMG tissue. These RGD-modified beads successfully induced cleft formation at the bead position, guiding the desired SMG morphology. Thus, this RGD-modified material might be a promising tool to modulate tissue growth and morphology in vitro for biological tissue fabrication.

Asunto(s)

RESUMEN

Mineralization is one of the most important processes in normal bone tissue development and in disease condition. Developing a novel and standardized in vitro model system that can readily monitor both cellular dynamics and mineralization is crucial for better understanding the bone tissue development and growth. Recent studies indicated that the mechanical environment is a critical condition in mineralization. We hypothesized that hydrogel with different mechanical stiffness can provide a biomimetic mechanical environment that can modulate bone tissue growth and mineralization. A femur of mouse embryo (embryonic day 16) was embedded in agarose hydrogel (2-60 kPa) and cultured in an osteogenic medium for a week. Microcomputed tomography (µCT) results revealed enhanced mineralization was detected in the femur head cultured in the gel condition, whereas no mineralization in the femur head cultured in the control (floating culture) condition. The mineralized region was corresponding to the region of secondary ossification center. Both histological and quantitative analyses indicated that the mineralized region of femur head cultured in 10 kPa gel condition was the highest and the mineralized area was significantly larger than that cultured in 2, 40, and 60 kPa gel condition. Immunofluorescence results indicated the enhanced mineralization caused by the higher chondrogenic differentiation at that region. This enhancement mainly relating to the mechanical forces and not to the oxygen tension was also confirmed. Since this system enhances and shortens the mineralization procedure compared with the conventional two-dimensional or three-dimensional cell culture system, this hydrogel system would be one of the unique models for better understanding the mineralized tissue development.

Asunto(s)

RESUMEN

Recent studies have established that, in benign tumors, a large number of cancer stem cells are present, which have great implications in tumor development. However, in ameloblastoma, a highly aggressive, locally invasive tumor with a high recurrence rate, whether or not cancer stem-like cells are present remains undetermined. Therefore, in this study we analyzed the protein expression of three candidate stem cell markers in ameloblastoma. Immunohistochemical staining for cancer stem cell (CSC) markers (CD133, CD44 and ABCG2) and for the proliferation marker Ki-67 was performed using 23 ameloblastoma cases. In all 23 samples, CD133, CD44 and ABCG2 were expressed. Nine (39.13%) cases showed high expression and 14 cases (60.87%) showed low expression for CD133. Twelve of the 23 cases (52.17%) showed high expression and 11 cases (47.83%) showed low expression for both CD44 and ABCG2, respectively. Ki-67 was mainly expressed in peripheral ameloblast-like cells, suggesting that these cells have a higher degree of differentiation and, therefore, are less likely to contain cancer stem-like cells. On the other hand, cells positive for CSC markers situated at the close proximity to peripheral cells were devoid of Ki-67 and may have the potential to be cancer stem-like cells. After analyzing the correlation between expression of three CSC markers with clinicopathological factors and Ki-67 expression, only CD44 expression was correlated with tumor recurrence (P=0.0391). In conclusion, this study showed various expression patterns of different types of cancer stem cell markers and the presence of candidate CSC-like cells in ameloblastoma, which are possibly involved in cell proliferation, tumor progression and recurrence.

RESUMEN

Secreted frizzled related protein (sFRP)-2, a Wnt antagonist, was strongly expressed by both stromal and tumor cells of ameloblastoma. The aim of this study is to evaluate whether sFRP-2 secreted from tumor cells have any direct role in suppressed bone formation or not. A pre-osteoblastic cell line, KUSA/A1 cells, cultured in conditioned medium of an ameloblastoma-derived cell line (AM-1CM) was used in the study. Alkaline phosphatase (ALP) activity, alizarin red staining, mineral quantification and MTS assay was performed. Wnt-canonical pathway is a major pathway for osteoblasts. Antagonists of this pathway, sFRP-1, 2 and 3, were detected by immunohistochemistry and western blot analysis. KUSA/A1 cells cultured in AM-1CM showed high cell proliferation, low ALP activity without mineralized matrix deposition. sFRP-2 was strongly expressed in ameloblastoma tissue and AM-1 cells. After sFRP-2 depletion, the cells showed diffuse mineralization. In this study, it was confirmed that ameloblastoma cells have a major role in decreased bone formation by secreting sFRP-2 in cell culture model. Though, sFRP-2 has great effect on tumor progression, inhibition of sFRP-2's anti-bone formation activity and cell proliferative activity may reduce the invasive property of ameloblastoma and possibility of recurrence rate.

Asunto(s)