| Tissue egineering is the emerging field of science aimed at developing techniques for the fabrication of new tissue to replace damaged tissues, which provided a new approach to treat periodontal disease and to reform the bone-implant interface. Polyglycolic acid (PGA), as a promising biomaterial, has many applications in bone, cartilage and ligament reconstruction. Based on the principles of tissue engineering, this study focused on assessing the biocompatibility of PGA non-woven mesh as scaffold to periodontal ligament cells (PDLCs), and observed the new tissue formation in vivo.Periodontal ligament tissues were taken from clinically healthy premolar teeth extracted for orthodontic reasons from patients. PDLCs were cultured in culturing plate until the fourth passage. Human PDLs were seeded onto 3D porous PGA fiber mesh scaffolds in a high density for 7 days' incubation in vitro. Then each of the twenty four BALB/c-nu mice was implanted with cell-PGA constructs and PGA only as control subcutaneously on the back bilaterally. The mice were scarified in batch at 1,2,3, 4 weeks and the harvests were examined histologically and immunohistochemically.The nude mice maintained normal in activity. Histological examination showed the degradation of PGA mesh and the proliferation of PDLCs. Type I collagens could be detected in 2 weeks of implantation. We calculated more collagen from the PDLCs in the experimental side comparing to the control side. In addition, the implants were well-vascularized from the second week in vivo. These results approve the biocompatibility of PGA mesh, suggesting that the delivery of PDLCs via non-woven PGA mesh may serve as a viable approach for promoting periodontal tissue regeneration and provides a possibility of PDL regeneration on dental implants.The periodontal ligament (PDL) is the fibrous connective tissue located between the alveolar bone and the root surface. The PDL is associated with important dental functions, in particular, the mechanisms in tooth support and tooth mastication, including proprioception. The PDL contains heterogeneous cell population, which are capable of expressing ragular factors that maintain PDL width through remodelling process, a homeostasis achieved by cell proliferation and apoptotic cell death. The PDLCs are believed to possess the capacity to regenerate the periodontium consisting of the PDL layer and surrounding alveolar bone and cementum. Biodegradable polymers have great potential for use in reconstruction of periodontal tissue as scaffold in tissue engineering.The scaffold materials should fulfill several preconditions, such as: high levels of biocompatibility and biodegradability, low degree of cytotoxicity and high affinity to biological surface. Furthermore, biodegradable biomaterials should provide mechanical support to the construct until the newly formed are structurally stabilized. PGA materials have approval by the US Food and Drug Administration (FDA) for human clinic use. The degredated product of PGA in vivo is carbon dioxide and water, which could be metabolized by body. In fact, they have been used for surgical sutures for many years. Non-woven PGA mesh have served as scaffold in the engineering of cartilage, bone, skin and skeletal muscle. The porosity of PGA fiber mesh sheets in this study is 97%. Prevenient study in vitro have proved this PGA scaffold to be excellent adhesiveness and biocompatibility, on which human periodontal ligament cells could maintain its morphological and biological property.In the fabrication of bioengineered periodontal tissue, the proliferation and ECM secretion of cells should fit for the degradation of polymer scaffold. Histological observation in vivo suggested that the scaffold degradated at same rate as tissue regeneration and was strong enough to withstand loading where necessary. The inflammation of the body was mild and decreased from the second week. The emergence of plenty of collagen, in particular Type I collagen from the cells, demonstrated good biocompatibility with the PGA scaffold.To replace the functions of a tissue completely, the engineered tissue must be fully integrated with the host body in terms of vascular supply. Vascularization of engineered tissue is critical. In this study, we observed migration of capillary vessels from one week, and abundant hot-blood-vessel ingrowths from 2 weeks time in the thin piece of new tissue, which should be enough to formulate the functional vascular network. The significant increase of blood vessels compared to the control side suggested that the seeding cells might influence the ingrowths of vessels from the surrounding tissues.Because of the merits mentioned above, non-woven PGA mesh may serve as a prospected scaffold in periodontal tissue engineering and provides a possibility of periodontal ligament regeneration on dental implants. Our results should contribute a better understanding of the cell-biodegradable scaffold interactions necessary to optimize the manufacturing and survival of tissue constructs.
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