Aspects of the invention relate to a novel mesenchymal stem cell line (hb-MSC), a culture medium conditioned by the hb-MSC line, and various hb-MSC compositions. The hb-MSC compositions may include a plurality of hb-MSCs, the hb-MSC conditioned medium, or a combination thereof. The hb-MSC compositions may also include one or more of an antimicrobial agent, a film-forming agent, an appropriate carrier, as well as other additives as determined by the application. Also described are methods of use for the hb-MSC cells, the conditioned medium, and the compositions, including methods of treating or preventing bovine mastitis.