Mesenchymal stem cells from the adipose tissue of patients with postoperative hernias produce excessive amounts of collagen III, which shifts the balance between type III and type I collagens. The proposed technique of pretransplantation preparation allows in vitro stimulation collagen formation processes with predominant activation of collagen I synthesis and normalization of proportion between different collagen types. Abdominal wall repair with polypropylene surgical mesh in combination with autotransplantation of mesenchymal stem cells reduced the collagen III to collagen I ratio due to activation of collagen I synthesis and suppression of collagen III production, which had a positive effect on the structure of in vivo formed connective tissue.