Three month old immunodeficient NSG mice NOD. Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice were purchased (Stock number: 005557, The Jackson Laboratory, Bar Harbor, ME) and maintained at the barrier facility of the Brown Foundation Institute of Molecular Medicine at the University of Texas Health Science Center at Houston. Mice were group-housed in ventilated cages, given acidified water and irradiated rodent diet (Purina, St Louis, MO) ad libitum, and maintained on a 12:12-h light: dark cycle. All experimental studies were carried out in accordance and approved by the Institutional Animal Care and Use Committee (IACUC) guidelines of The University of Texas Health Science Center at Houston. Mice were divided in three experimental groups (non-treated control, gel alone and gel/MDSC groups, n = 5 each).
For generation of the muscle defect, after induction of general anesthesia, hindlimb was disinfected using chlorhexidine followed by 70% ethanol. A small incision (5 mm) was made over the tibialis anterior (TA) to expose the muscle. The muscle defect was created by removing a 4 × 2 × 2mmpartial thickness wedge resection using iris scissors (FST, Foster City, CA). If needed, hemostasis was achieved by gentle pressure with sterile cotton swaps. Then the fascia and skin were sutured using a 5-0 PDSII suture (Ethicon, Cincinnati, OH).
For generation of the muscle defect, after induction of general anesthesia, hindlimb was disinfected using chlorhexidine followed by 70% ethanol. A small incision (5 mm) was made over the tibialis anterior (TA) to expose the muscle. The muscle defect was created by removing a 4 × 2 × 2mmpartial thickness wedge resection using iris scissors (FST, Foster City, CA). If needed, hemostasis was achieved by gentle pressure with sterile cotton swaps. Then the fascia and skin were sutured using a 5-0 PDSII suture (Ethicon, Cincinnati, OH).