Lymphangiogenesis: novel strategies to promote cutaneous wound healing

In-vivo immunocompatibility and induced regenerative potential of silk fibroin modified decellularized porcine liver scaffolds in rat subcutaneous and full-thickness abdominal wall defect models

For reconstructive surgical applications, humoral and cell-mediated immune response to scaffolds is important in determining its structural and functional integration and performance. A decellularized porcine liver matrix(DPL) mechanically augmented with impregnating silk fibroin(SF100DPL) and silk fibroin-gelatin blends(SFG5050DPL and SFG3070DPL) following citric acid crosslinking were evaluated in-vitro and in-vivo (subcutaneous and abdominal wall defect models) in comparison to unmodified DPL. Ensuring the preservation of glycosaminoglycan and the potential to induce cell migration in L929 cell line, the host immunocompatibility of the scaffolds was confirmed by implanting sub-cutaneously in rat. The modified scaffolds in the full-thickness rat abdominal wall defect model showed better integration at the defect site without any evidence of mechanical failure. The inflammatory cell response was evidently reducing with prominent neovascularization. Masson's trichrome (MT) staining and immunohistochemistry (IHC) demonstrated skeletal muscle island formation initially at the host-graft interface while extending towards the mid-graft region as time progressed. A significant decrease in the collagen III/I ratio at 90 days indicated that the neocollagen deposited at 21 days was replaced by mature collagen type I. Among the modified scaffolds evaluated, the SF100DPL and SFG5050DPL exhibited comparatively high immunocompatibility and regenerative potential that makes them suitable for various scaffold based regenerative therapies.

Inhibition of Th2 Differentiation Accelerates Chronic Wound Healing by Facilitating Lymphangiogenesis

Background/Objectives: Chronic wounds pose a significant healthcare burden, and there remains no effective animal model for study. We aimed to develop a mouse model of chronic wounds that remain open for at least 4 weeks and to investigate the role of the lymphatic system in wound healing. Methods: Full-thickness excisional wounds were created on the dorsal surface of mouse tails to simulate chronic wounds. Lymphatic drainage was assessed using FITC-dextran lymphangiography. Histology and immunofluorescence were used to analyze immune cell infiltration. The effect of inhibiting Th2 differentiation via IL-4 and IL-13 neutralization on wound closure was also evaluated. Results: Our chronic wound model was successful, and wounds remained open for 4 weeks. Impaired lymphatic drainage was observed extending beyond the wound area. Increased CD4+ T-helper cell infiltration and Th2 cell accumulation were observed in the impaired lymphatic drainage zone. Inhibition of IL-4 and IL-13 accelerated wound healing. Conclusions: Impaired lymphatic drainage and Th2-mediated inflammation contribute to delayed healing, and gradients of lymphatic fluid flow are associated with spatial differences in lymphangiogenesis. Targeting Th2 cytokines may offer a novel therapeutic approach for chronic wounds.