Recently, it has been reported that mesenchymal stem cell (MSC)-derived humoral factors promote skin wound healing. As these humoral factors are transiently stored in cytoplasm, we collected them as part of the cell extracts from MSCs (MSC-ext). This study aimed to investigate the effects of MSC-ext on skin wound healing. We examined the effects of MSC-ext on cell proliferation and migration. Additionally, the effect of MSC-ext on skin wound healing was evaluated using a mouse skin defect model. The MSC-ext enhanced the proliferation of dermal fibroblasts, epithelial cells, and endothelial cells. It also increased the number of migrating fibroblasts and epithelial cells. The skin defects treated with MSC-ext demonstrated rapid wound closure compared to those treated with phosphate-buffered saline. The MSC-ext group exhibited a thicker dermis, larger Picrosirius red-positive areas, and a higher number of Ki67-positive cells. Our results indicate that MSC-ext promotes the proliferation and/or migration of fibroblasts, epithelial cells, and endothelial cells, and enhances skin wound healing. This suggests the therapeutic potential of MSC-ext in treating skin defects as a novel cell-free treatment modality.

Epigallocatechin gallate (EGCG)—the most abundant catechin in green tea—is a promising component of advanced composite biomaterials. The pharmacological activity of EGCG is typically attenuated upon thermal processing, although the exact effects of heating free and modified EGCG in air and vacuum are unknown. To bridge this gap, we herein examined the effects of heating free and modified (in gelatin containing beta-tricalcium phosphate granules) EGCG in vacuum and air (100–220 °C, 1–16 h) on its physicochemical and antioxidant properties using water and ethanol solubility measurements, discoloration and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) assays, ultraviolet–visible spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy, and attenuated total reflectance Fourier transform infrared spectroscopy. The antioxidant activity of EGCG-modified gelatin sponges was assessed in vitro using the DPPH assay and in vivo using a calvarial bone defect model in eight-week-old male Sprague–Dawley rats. Free and modified EGCG showed antioxidant activities, which were largely retained after heating in vacuum at 150 °C. These findings show that appropriate heating procedures preserve the antioxidant activity of EGCG and provide insights for the development of EGCG-based biomaterials.

Orthodontic force magnitude influences angiogenesis during orthodontic tooth movement (OTM); however, the role of senescent cells remains largely unclear. This study investigated the localization of senescent cells and their expression of vascular endothelial growth factor (VEGF) during angiogenesis using a rat horizontal OTM model with different force magnitudes. Nickel–titanium coil springs exerting 60 g or 180 g of orthodontic force were applied to the maxillary first molar of 15-week-old male Sprague–Dawley rats; untreated rats served as controls. Tooth movement was evaluated by stereomicroscopy and micro-computed tomography. Senescent cells (p21, p16) and angiogenesis (CD31 and VEGF) were evaluated by multiplex immunofluorescence. Tooth movement was observed under both the 60 g and 180 g conditions. The 60 g group showed increased cellularity, vascular density, and VEGF expression, suggesting an optimal mechanical force. In contrast, the 180 g group reduced cellularity and angiogenesis, consistent with excessive force. Senescent cells were more abundant in the 60 g group, with over 40% expressing VEGF. These findings suggest that force magnitude influences the presence of VEGF⁺ senescent cells, which may be associated with the angiogenic process in OTM. This work provides insights into the mechanisms underlying optimal force in orthodontic treatment.