Surgical procedures were aseptically performed in the Animal Facility operating rooms. A full-thickness skin wound (10 mm × 10 mm) was excised from the dorsum of normal C57BL/6 mice. Segments of the bilayer artificial skin replacement Integra® (Integra LifeSciences Corporation, Plainsboro, NJ) were sutured to the adjoining skin and underlying muscle with 6.0 nylon suture. No dressing was applied.
A volume of 100 μl of 0.8% methylcellulose was then delivered with a micropipette, between the Integra® layer and the adjacent tissue. Animals were assigned to three groups, with 18 mice per group. The first group (control, C group) received only methylcellulose, whereas mice in the second group received methylcellulose containing 105 eGFP-positive bone marrow cells (BM group) and the third group was treated with methylcellulose containing 104 eGFP-positive mesenchymal stem cells (MSC group).
Four, eight and sixteen days after the surgery, six mice from each group were euthanized, the wounds were harvested and frozen sections were prepared for histological and immunohistochemical staining.