143 Therapeutic efficacy and safety of adipose tissue-derived mesenchymal stem cells in treating mastitis and metritis in dairy cattle

Abstract

Mastitis and metritis are two inflammatory diseases with high economic impact on dairy industry and farmers are losing revenues. Antibiotic treatment for these disease conditions typically achieve suboptimal outcomes. Moreover, emerging antibiotic resistance in mastitis and metritis worldwide has a severe effect on productivity, fertility, and lifespan of animals. A paradigm shift in treatment strategies is much needed for these animals. Attracting properties of mesenchymal stem cells may act as an alternative strategy for treating these diseases. In addition to their ability to differentiate into multiple types of cells, mesenchymal stem cells can orchestrate immune responses and modulate tissue microenvironments. In the present study, we evaluated the safety and efficacy of adipose tissue–derived mesenchymal stem cells (AT-MSC) for mastitis and metritis. A well-characterised adipose-derived stem cell line with 3–5 passages cells were used for treatment for these diseases. In a safety trial, mastitis- and metritis-infected cattle were administered with 1 × 10⁶ cells of AT-MSC through different routes (local, IV, IV+local). Animals were clinically evaluated during 15 days of the experimental period and blood samples were collected for hemogram determination. The efficacy was checked under both in vivo and in vitro conditions. In vitro efficiency of AT-MSC was determined using a transwell plate experiment, in which AT-MSC were co-cultured with bacteria (Escherichia coli and Staphylococcus). In vivo efficiency was evaluated by administration of in 2 mL (1 × 10⁶ cells) of AT-MSC dose; then, somatic cell count (SCC) in milk of mastitic cattle and polymorphonuclear (PMN) cell count in cervical vaginal fluid (CVF) of metritic cattle were determined. Gene expression profiling of antimicrobial (cathelicidin, lipocalin, cystatin) and anti-inflammatory (IL-4, IL-6, IL-10) peptides were quantified in all groups: IV, local, IV+local, and control ATB (antibiotic). Allogenic AT-MSC did not induce any immunological rejection response in treated animals. A significant reduction of bacteria in CVF in vitro when co-cultured with AT-MSC was observed. The PMN count was significantly reduced in CVF of the IV+local group. The SCC in milk of mastitic animals was decreased in the local (intramammary) group. Maximum expression of IL-6, IL-10, cathelicidin, lipocalin, and cystatin and angiopoietin genes were observed on Day 3 followed by Day 7 in the local group in case of mastitis. In metritis, expression of IL-6, IL-10, cathelicidin, lipocalin, cystatin, and angiopoietin were observed at Day 3 in the IV+local group. All mastitic and metritic cattle were completely and permanently cured within 30 days after treatment with mesenchymal stem cells. In conclusion, we provide initial evidence for the use of allogenic AT-MSC and their safety and efficacy to treat mastitis and metritis in dairy cattle.