Induced pluripotent stem cells transplantation as wound therapy on a mouse model

Abstract

Stem cell transplantation represents a relatively new approach of treating wounds, with several studies reporting positive results. Yet these studies used stem cells that are limited by the following: differential potency, ethical permissibility, or histocompatibility. To overcome these obstructions, induced pluripotent stem (iPS) cells, a type of stem cell that can be generated from cells of a patient, was used in this study instead. This study aims to culture and graft iPS cells into mice with the splinted wound mouse model and determine the effectiveness of the treatment. 18 clinically healthy female mice were immunosuppressed with a daily intramuscular injection of dexamethasone at 1 µg/g for three consecutive days. Under anaesthesia, two sterile wounds were incised on shaved backs of each mouse via biopsy punch. Subsequently, six intradermal injections were made around the two wounds before the wounds were adhered with splints and wound dressing. The mice were divided into two groups; a treatment group that was given 7 × 105 iPS cells in each injection, and a control group that was given 0.9 % sodium chloride. Wound closure rates were determined through timed scaled photography and subsequent analyses with GNU Image Manipulation Program. Three mice were euthanised from each group at every seven days post-wounding, at which point wound beds and blood were harvested. Total leucocyte counts and differential leucocyte counts were conducted on the blood. Wound beds were fixed, processed, blocked, and sectioned. Sections were used in fluorescence in situ hybridization (FISH) to detect iPS cells of male origin in female hosts. Sections were also stained with H&E and Masson’s Trichrome, as well as immunolabeled for CD31 and KI67. The stained sections were then subjected to an evaluation under compound microscopy and subsequently scored for several variables. FISH revealed that the transplanted iPS cells were successfully grafted and may survive permanently. KI67-immunostained sections revealed no difference between groups; together with the fact that no tumours were found throughout the study, the risk of teratoma formation seems to be low. Total and differential leucocyte counts showed no difference between groups. The wound closure curve of the treatment group was stiffer, yet the difference was not significant, however individual results were significantly different for day 7 (p = 0.038). From the evaluation and scoring, the treatment group scored better in chronic inflammation, fibroblast proliferation, granulation tissue, and collagen deposition, albeit not statistically significant. However, the treatment group did score significantly better in angiogenesis (p = 0.006 for day 7) and hypodermis regeneration (p = 0.006 for day 21).