Treatment of Skin Wounds in Old Animals Using Mesenzymal Progenitor Cells and Polymer Gel Compositions

Purpose: An assessment of the effectiveness of progenitor mesenchymal stem cell as injections and as part of a polymer hydrogel for the wounds healing in old animals.

Materials and Methods: Fixed-size wounds (average area of 135.8 mm2) were modelled on the backs of 9-month-old white Wistar rats. On the modelling day, mesenchymal stem cells (MSC) isolated from a human umbilical cord were injected into the wounds once (SC group). In other animals, MSC were applied externally on a regular basis as one of the components in the polymer hydrogel (Polymer sc group). The systemic effect of the cells was evaluated by examining intact contralateral wounds on the opposite side of the same animal's back (control sc and Control Psc groups, respectively). The intact reference wounds belonged to the Control 0 group. The wound area was studied in dynamics. Descriptive microscopy was supplemented by an assessment of the collagen fibers' maturity, the epidermal layers, and the number of fibroblasts and leukocytes in different parts of the wounds.

Results: MSC application, both local and systemic, resulted in improved wound regeneration. The method and location of application had no effect on the dynamics of wound healing during the acute inflammatory phase (up to 3 days). Polymer_sc was ultimately found to be the most effective. MSC's anti-inflammatory effect was confirmed by a reduction in leukocyte infiltration in wound centres (Polymer_sc and SC groups) and edges (all groups, with the greatest extent in the Polymer_sc group). The Control_Psc group, particularly the Polymer_sc group, was affected by the proliferative phase, which manifests itself as accelerated growth in fibroblast number and collagen production.

Conclusion: MSC applications improve and accelerate wound healing in a variety of ways, even in old animals. The best performance was achieved in the Polymer_sc group.