External application of human umbilical cord-derived mesenchymal stem cells in hyaluronic acid gel repairs foot wound of type I and type II diabetic rats through paracrine action mode

Abstract:

Background: Diabetic foot ulcer (DFU) is a main complication of diabetes mellitus with high rate of amputation and low rate of therapeutic success. External application of mesenchymal stem cells (MSCs) provides a new therapeutic option to treat DFU and avoids the drawbacks of injective MSCs therapy. In this study, human umbilical cord-derived MSCs-hyaluronic acid gel (hucMSCs-HA gel) was developed for evaluating the external efficacy of MSCs on DFU, and its paracrine mode of action was explored by using hucMSCs-conditional medium (MSC-CM).

Methods: In vivo, type I and type II diabetic rat models were established and received hucMSCs-HA gel external treatment, and histopathological staining (HE and Masson) and immunohistochemical analysis were conducted. In vitro, human umbilical vein endothelial cells (HUVECs) and human skin fibroblasts (HSFs) were exposed to high glucose and received MSC-CM treatment, and the assays of cell viability, wound healing, transwell migration, tube formation, cell senescence, reactive oxygen species (ROS), malondialdehyde (MDA) detection, qRT-PCR, and Western blot were conducted. The in vivo data indicated that hucMSCs-HA gel accelerated DFU healing in both type I and type II diabetic rats by improving re-epithelialization, collagen deposition, and angiogenesis, in which hucMSCs played a major role in the gel.

Results: The in vitro data demonstrated that MSC-CM not only improved cell viability, wound healing, migration, tube formation, and cell senescence of HUVECs, but also promoted cell viability, accelerated wound healing, and reduced ROS and MDA production of HSFs, suggesting a paracrine mode of action of hucMSCs in treatment of DFU. Moreover, MSC-CM significantly restored the abnormal expressions of pro-inflammatory and antiangiogenic genes (TNF-α, IL-1β, IL-6, ET-1 and p16) and proliferative protein (PCNA) of HUVECs, and also restored the pro-fibrotic and antioxidant genes (COL1A1, COL3A1, COL4A1, SOD1 and SOD2) and proteins (PCNA and COL1) of HSFs.

Conclusions: These results suggested that hucMSCs-HA gel facilitated DFU healing of type I and type II diabetic rats mainly through paracrine actions on HUVECs and HSFs. This study provided new insights into MSCs therapy and a promising therapeutic strategy for the clinical treatment of DFU.