RESUMEN
A vital and healthy dental pulp (DP) is required for teeth to remain functional throughout a lifespan . Appreciating its value for the tooth, the regeneration of the DP is a highly researched goal. While inflammation of the DP marks the beginning of an eventual necrosis, it is also the prerequisite for the regenerative events of neovascularisation, stem cells mobilisation and reparative dentine deposition. In the light of a pro-regenerative inflammatory process, the present review discusses the role of macrophage population shift from pro- to anti-inflammatory in reversible versus irreversible pulpitis, while also analysing the overlooked contribution of pulp innervation and locally derived neuropeptides to the process. Then, the currently practiced (pulp capping and revascularisation) and researched (cells transplantation and cell homing) approaches for DP regeneration are discussed. Focusing on the role of cell homing in modulating inflammation, some potential strategies are highlighted to harness the inflammatory process for DP regeneration, mainly by reversing inflammation through macrophage induction. Next, some potential clinical applications are discussed - especially with capping materials - that could boost macrophage polarisation and complement system activation. Finally, current challenges facing the regeneration of the DP are presented, while underlining the importance of promoting an anti-inflammatory environment conducive to a regenerative process.
Asunto(s)
Pulpa Dental , Pulpitis , Humanos , Inflamación , RegeneraciónRESUMEN
In the current theme of dental pulp regeneration, biological and synthetic scaffolds are becoming a potential therapy for pulp revitalization. The goal is to provide a suitable environment for cellular infiltration, proliferation, and differentiation. The extracellular matrix (ECM) represents a natural scaffold material resembling the native tissue chemical and mechanical properties. In the past few years, ECM-based scaffolds have shown promising results in terms of progenitor cells recruitment, promotion of constructive remodeling, and modulation of host response. These properties make ECM-derived scaffolds an ideal candidate for pulp regenerative therapy. Development of strategies for clinically relevant tissue engineering using dental pulp extracellular matrix (DP-ECM) can provide an alternative to conventional root canal treatment. In this work, we successfully decellularized ECM derived from porcine dental pulp. The resulting scaffold was characterized using immunostaining (collagen type I, dentin matrix protein 1, dentin sialoprotein, and Von Willebrand factor) and enzyme-linked immunosorbent assay (transforming growth factor ß, vascular endothelial growth factor, and basic fibroblast growth factor) for extracellular proteins where the ECM retained its proteins and significant amount of growth factors. Furthermore, a pilot in vivo study was conducted where the matrix was implanted for 8 wk in a dog root canal model. Our in vitro and preliminary in vivo data show that the decellularized ECM supports cellular infiltration together with the expression of pulp-dentin and vascular markers (DSP and CD31) compared to the controls. Herein, we show the feasibility to produce a decellularized ECM scaffold and validate the concept of using ECM-based scaffolds for pulp regeneration.
Asunto(s)
Pulpa Dental/citología , Matriz Extracelular/química , Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Animales , Biomarcadores/análisis , Diferenciación Celular , Proliferación Celular , Microambiente Celular/fisiología , Proteínas de la Matriz Extracelular/química , Modelos Animales , Proyectos Piloto , Regeneración/fisiología , Células Madre/citología , PorcinosRESUMEN
Mechanical load influences bone structure and mass. Arguing the importance of load-transduction, we investigated the mechanisms inducing bone formation using an elastomeric substrate. We characterized Poly (glycerol sebacate) (PGS) in vitro for its mechanical properties, compatibility with osteoprogenitor cells regarding adhesion, proliferation, differentiation under compression versus static cultures and in vivo for the regeneration of a rabbit ulna critical size defect. The load-transducing properties of PGS were compared in vitro to a stiffer poly lactic-co-glycolic-acid (PLA/PGA) scaffold of similar porosity and interconnectivity. Under cyclic compression for 7days, we report focal adhesion kinase overexpression on the less stiff PGS and upregulation of the transcription factor Runx2 and late osteogenic markers osteocalcin and bone sialoprotein (1.7, 4.0 and 10.0 folds increase respectively). Upon implanting PGS in the rabbit ulna defect, histology and micro-computed tomography analysis showed complete gap bridging with new bone by the PGS elastomer by 8weeks while minimal bone formation was seen in empty controls. Immunohistochemical analysis demonstrated the new bone to be primarily regenerated by recruited osteoprogenitors cells expressing periostin protein during early phase of maturation similar to physiological endochondral bone development. This study confirms PGS to be osteoconductive contributing to bone regeneration by recruiting host progenitor/stem cell populations and as a load-transducing substrate, transmits mechanical signals to the populated cells promoting differentiation and matrix maturation toward proper bone remodeling. We hence conclude that the material properties of PGS being closer to osteoid tissue rather than to mineralized bone, allows bone maturation on a substrate mechanically closer to where osteoprogenitor/stem cells differentiate to develop mature load-bearing bone. SIGNIFICANCE OF SIGNIFICANCE: The development of effective therapies for bone and craniofacial regeneration is a foremost clinical priority in the mineralized tissue engineering field. Currently at risk are patients seeking treatment for craniofacial diseases, traumas and disorders including birth defects such as cleft lip and palate, (1 in 525 to 714 live births), craniosynostosis (300-500 per 1,000,000 live births), injuries to the head and face (20 million ER visits per year), and devastating head and neck cancers (8000 deaths and over 30,000 new cases per year). In addition, approximately 6.2 million fractures occur annually in the United States, of which 5-10% fail to heal properly, due to delayed or non-union [1], and nearly half of adults aged 45-65 have moderate to advanced periodontitis with associated alveolar bone loss, which, if not reversed, will lead to the loss of approximately 6.5 teeth/individual [2]. The strategies currently available for bone loss treatment largely suffer from limitations in efficacy or feasibility, necessitating further development and material innovation. Contemporary materials systems themselves are indeed limited in their ability to facilitate mechanical stimuli and provide an appropriate microenvironment for the cells they are designed to support. We propose a strategy which aims to leverage biocompatibility, biodegradability and material elasticity in the creation of a cellular niche. Within this niche, cells are mechanically stimulated to produce their own extracellular matrix. The hypothesis that mechanical stimuli will enhance bone regeneration is supported by a wealth of literature showing the effect of mechanical stimuli on bone cell differentiation and matrix formation. Using mechanical stimuli, to our knowledge, has not been explored in vivo in bone tissue engineering applications. We thus propose to use an elastomeric platform, based on poly(glycerol sebacate (PGS), to mimic the natural biochemical environment of bone while enabling the transmission of mechanical forces. In this study we report the material's load-transducing ability as well as falling mechanically closer to bone marrow and osteoid tissue rather than to mature bone, allowed osteogenesis and bone maturation. Defying the notion of selecting bone regeneration scaffolds based on their relative mechanical comparability to mature bone, we consider our results in part novel for the new application of this elastomer and in another fostering for reassessment of the current selection criteria for bone scaffolds.
Asunto(s)
Regeneración Ósea/efectos de los fármacos , Decanoatos , Elastómeros , Glicerol/análogos & derivados , Ácido Láctico , Ácido Poliglicólico , Polímeros , Andamios del Tejido/química , Cúbito , Animales , Decanoatos/química , Decanoatos/farmacología , Elastómeros/química , Elastómeros/farmacología , Femenino , Glicerol/química , Glicerol/farmacología , Ácido Láctico/química , Ácido Láctico/farmacología , Ácido Poliglicólico/química , Ácido Poliglicólico/farmacología , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Polímeros/química , Polímeros/farmacología , Conejos , Ratas , Ratas Sprague-Dawley , Cúbito/lesiones , Cúbito/metabolismo , Cúbito/patologíaRESUMEN
The human innate regenerative ability is known to be limited by the intensity of the insult together with the availability of progenitor cells, which may cause certain irreparable damage. It is only recently that the paradigm of tissue engineering found its way to the treatment of irreversibly affected body structures with the challenge of reconstructing the lost part. In the current review, we underline recent trials that target engineering of human craniofacial structures, mainly bone, cartilage, and teeth. We analyze the applied engineering strategies relative to the selection of cell types to lay down a specific targeted tissue, together with their association with an escorting scaffold for a particular engineered site, and discuss their necessity to be sustained by growth factors. Challenges and expectations for facial skeletal engineering are discussed in the context of future treatment.
Asunto(s)
Cartílago/anatomía & histología , Huesos Faciales/anatomía & histología , Regeneración/fisiología , Cráneo/anatomía & histología , Ingeniería de Tejidos , Diente/anatomía & histología , Animales , Humanos , Péptidos y Proteínas de Señalización Intercelular/uso terapéutico , Neovascularización Fisiológica/fisiología , Células Madre/fisiología , Andamios del Tejido/clasificaciónRESUMEN
The heterogeneous population of non-haematopoietic cells residing in the bone marrow (bone marrow stromal cells, BMSCs) and the different fractions and components obtained from platelet-rich plasma provide an invaluable source of autologous cells and growth factors for bone and other connective tissue reconstruction. In this study, we investigated the effect of an allogenic platelet lysate on human BMSCs proliferation and differentiation. Cell proliferation and number of performed cell doublings were enhanced in cultures supplemented with the platelet-derived growth factors (platelet lysate, PL), either with or without the concomitant addition of fetal bovine serum (FBS), compared to cultures performed in the presence of FBS and FGF2. Both in vitro and in vivo osteogenic differentiation were unaltered in cells maintained in medium supplemented with PL and not FBS (Only PL) and in cells maintained in medium containing FBS and FGF2. Interestingly, the in vitro cartilage formation was more effective in the pellet of BMSCs expanded in the Only PL medium. In particular, a chondrogenic differentiation was observed in pellets of some in vitro-expanded BMSCs in the Only PL medium, whereas pellets from parallel cell cultures in medium containing FBS did not respond to the chondrogenic induction. We conclude that the platelet lysate from human source is an effective and even more beneficial substitute for fetal bovine serum to support the in vitro expansion of human BMSCs for subsequent tissue-engineering applications.