Decellularization is the process of removing the cellular components from tissues or organs. It is a promising technology for obtaining a biomaterial with a highly preserved extracellular matrix (ECM), which may also act as a biological scaffold for tissue engineering and regenerative therapies. Decellularized products are gaining clinical importance and market space due to their ease of standardized production, constant availability for grafting and mechanical or biochemical superiority against competing clinical options, yielding clinical results ahead of the ones with autografts in some applications. Current drawbacks and limitations of traditional treatments and clinical applications can be overcome by using decellularized or acellular matrices. Several companies are leading the market with versatile acellular products designed for diverse use in the reconstruction of tissues and organs. This review describes ECM-based decellularized and acellular products that are currently in use for different branches of clinic.

Periodontal tissue engineering is expected to overcome the limitations associated with the existing regenerative techniques for the treatment of periodontal defects involving alveolar bone, cementum, and periodontal ligament. Cell-based tissue engineering approaches involve the utilization of in vitro expanded cells with regenerative capacity and their delivery to the appropriate sites via biomaterial scaffolds. The aim of this study was to establish living periodontal ligament cell-containing structures on electrospun poly(DL-lactic-co-glycolic acid) (PLGA) nanofiber membrane scaffolds, assess their viability and characteristics, and engineer multilayered structures amenable to easy handling. Human periodontal ligament (hPDL) cells were expanded in explant culture and then characterized morphologically and immunohistochemically. PLGA nanofiber membranes were prepared by the electrospinning process; mechanical tensile properties were determined, surface topography, nanofiber size, and porosity status were investigated with SEM. Cells were seeded on the membranes at approximately 50,000 cell/cm(2) and cultured for 21 days either in expansion or in osteogenic induction medium. Cell adhesion and viability were demonstrated using SEM and MTT, respectively, and osteogenic differentiation was determined with IHC and immunohistomorphometric evaluation of osteopontin, osteocalcin, and bone sialoprotein marker expression. At days 3, 6, 9, and 12 additional cell/membrane layers were deposited on the existing ones and multilayered hybrid structures were established. Results indicate the feasibility of periodontal ligament cell-containing tissue-like structures engineering with PDL cells and electrospun nanofiber PLGA scaffolds supporting cell adhesion, viability and osteogenic differentiation properties of cells in hybrid structures amenable to macroscopic handling.

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The objective of this study was to assess the in vitro release kinetics and the in vivo angiogenic effect of human vascular endothelial growth factor (VEGF)-activated poly(DL-lactide-co-glycolide) (PLGA) sponge. The highly porous sponges (each 3 x 4 x 4 mm(3)) were activated by soaking in a VEGF solution (2.5 or 5.0 microg) and then freeze-drying. In vitro release in PBS was investigated by a competitive enzyme immunoassay for up to 3 weeks. The burst-type initial release within the first 3 days followed a more controlled one lasting for >2 weeks. The angiogenic potential of the VEGF sponge was evaluated by subcutaneous implantation into the epigastric groin fascia of Wistar rats. Histomorphometry and SEM confirmed the formation of new capillaries infiltrating the sponge pores starting from the first week and the drastic anostomosis at weeks 2 and 3. However, the rats implanted with control sponges or receiving VEGF injection exhibited much lower or no angiogenic response, respectively. TEM revealed the neo-vessels had a single endothelial layer surrounded by the matrix inoculated with the rat circulation. The results indicate that VEGF-activated PLGA sponge can be considered as a tool to establish neovascularized subcutaneous transplantation sites for tissue-engineering applications.