Safety of Intraperitoneal Injection of Adipose Tissue-Derived Autologous Mesenchymal Stem Cells in Cats.

Background: Chronic inflammatory diseases are common in cats and mesenchymal stem cells (MSC) are a promising therapeutic approach for management of these disorders. The purpose of this study was to evaluate the safety of intraperitoneal injection of MSC in cats. Hypothesis: Intrapertioneal injection of autologous MSC in cats is safe. Animals: Ten healthy adult purpose-bred cats. Methods: Mesenchymal stem cells were isolated from subcutaneous adipose tissue collected during ovariohysterectomy and characterized for expression of CD90, CD105 and CD44 and trilineage differentiation. Three weeks postoperatively a complete blood count, serum chemistry profile, urinalysis, and abdominal ultrasound were performed. Five cats then received 1 9 10 6 of autologous MSC/kg of body weight intraperitoneally with ultrasound guidance; 5 additional cats were sham injected. Cats were monitored for 6 weeks with daily physical examinations and weekly clinicopathological evaluations. Abdominal ultrasonography was repeated at weeks 1 and 5 after injection. Results: Serious adverse effects were not observed in any MSC-injected cat. Two animals developed transient lethargy and decreased activity. Jejunal lymph node size was increased in MSC-injected cats compared to controls at weeks 1 (1.38 +/- 0.25 versus 0.88 +/- 0.25 cm(2); P =.036) and 5 (1.75 +/- 0.82 versus 0.79 +/- 0.12 cm(2); P = .047). A hyperechoic renal segmental cortical lesion was observed in 1 MSC-injected cat. Conclusions and Clinical Relevance: Intraperitoneal MSC injection was well tolerated with only mild, self-limiting adverse effects being observed in 2 cats. This route provides a safe means of administration for cell-based treatment in cats.