In vivo research on 3D-printed composite PLGA and PDLLA-HA absorbable scaffolds for repairing radius defects in rabbits.

OBJECTIVES: Despite being an important research topic in oral biomaterials, few studies have demonstrated the differences between poly(d,l-lactide-co-glycolide)/hydroxyapatite (PLGA/HA) and poly(d,l-lactic acid)/hydroxyapatite (PDLLA/HA). In this study, PLGA/HA and PDLLA/HA scaffolds were prepared using three-dimensional (3D) printing technology and implanted into radius defects in rabbits to assess their effects on bone regeneration. METHODS: In this study, 6 mm × 4 mm bone defects were generated in the bilateral radii of rabbits. 3D-printed PLGA/HA and PDLLA/HA scaffolds were implanted into the defects. X-ray imaging, micro-computed tomography, and hematoxylin-eosin staining were performed to observe the degradation of the materials, the presence of new bone, and bone remodeling in the bone defect area. RESULTS: The PLGA/HA scaffolds displayed complete degradation at 20 weeks, whereas PDLLA/HA scaffolds exhibited incomplete degradation. Active osteoblasts were detected in both groups. The formation of new bone, bone marrow cavity reconstruction, and cortical bone remodeling were better in the PLGA/HA group than in the PDLLA/HA group. CONCLUSIONS: PLGA/HA scaffolds performed better than PDLLA/HA scaffolds in repairing bone defects, making the former scaffolds more suitable as bone substitutes at the same high molecular weight.

Cartilaginous Extracellular Matrix Enriched with Human Gingival Mesenchymal Stem Cells Derived "Matrix Bound Extracellular Vesicles" Enabled Functional Reconstruction of Tracheal Defect.

Stem cells derived extracellular vesicles (EVs) conceive cues essential for tissue repair. Mammalian cartilaginous extracellular matrix (cECM) may not be optimally inductive for tracheal regeneration because of the granulomatous, instead of regenerative, responses in injured adult mammalian tracheas. Given the high regenerative capacity of gingiva, it is hypothesized human gingival mesenchymal stem cells derived EVs (gEVs) can induce mammalian tracheal epithelia regeneration. Coculturing chondrocytes with GMSCs produce abundant "matrix bound gEVs (gMVs)" in forming cartilaginous ECM, which are further preserved in acellular cECM (cACM) following mild, short-period decellularization. The results show that gMVs-cACM could be well anchored on polyglycerol sebacate microporous patch thus enforce the surgical suturability and mechanical strength. In rabbit tracheal defect, the gMVs-cACM patch induces rapid regeneration of vascularized ciliated columnar epithelium, which supports long-term survival of animals. gMVs-cACM treated groups exhibit proliferation of tracheal progenitors-basal epithelial cells, as well as, activation of JAK2/STAT1 pathway in reparative cells. This study departs from conventional focuses on tissue derived ECM and introduces a new approach for tracheal tissue regeneration.