EFFECT OF RAT MESENCHYMAL STEM-CELLS ON DEVELOPMENT OF ABDOMINAL ADHESIONS AFTER SURGERY

One of the common and most serious side effects of abdominal surgery i s the formation of adhesions within the peritoneal cavity during heali ng. Efforts to prevent adhesion formation have concentrated on inhibit ing the inflammatory response, inhibiting the formation or encouraging the lysis of fibrin, and protection of the damaged serosal surface. W e are interested in regenerating the serosal surface by providing a so urce of mesothelial progenitor cells, Rats were divided into groups of 10 each. Abdominal adhesions were created by removing a circle of per itoneum and suturing it back into place. Two weeks later the rats were euthanized and the adhesions scored on a scale of 0-5, A population o f mesenchymal stem cells (MSCs) isolated from the skeletal muscle of n eonatal rats was tested. The cells were grown in primary culture to ex pand the population and then trypsinized and frozen at -80 degrees C. They are then thawed and grown in secondary culture before use. The co ntrol group were injected with saline ip immediately after surgery, Th e experimental groups received (1) 1.4 x 10(6) MSCs, (2) 5 x 10(6) MSC s, (3) 7.5 x 10(6) dead MSCs, (4) 5 x 10(6) rat smooth muscle cells im mediately post-op, and (5) 5 x 10(6) MSCs 4-6 hours after surgery, Onl y live MSCs given immediately after surgery by ip injection significan tly decreased the adhesion scores of the rats (mean score of 3.5 vs 0. 9), MSCs injected ip 4-6 hours after surgery actually increased the ad hesion scores (3.5 vs 4.7), and rat smooth muscle cells injected ip im mediately after surgery had no effect on adhesions. The exact mechanis m of action of the MSCs is unknown at this time, However, we postulate that the MSCs have the capacity to differentiate into mesothelial cel ls capable of repopulating the injured mesothelium. (C) 1996 Academic Press, Inc.