Mesenchymal stem cells from Wharton’s jelly in domestic animals.

Wharton's jelly (WJ) derives from extra embryonic mesoderm, and is largely made up of mucopolisaccharides serving for the developing fetus. Indeed, its cells contain gelatin-like mucus that encase fiber: these properties give it an elastic and cushion effect, which can tolerate the vibration, bending, stretching and twisting of an active fetus. In addition, WJ holds vessels together, may regulate blood flow, plays a role in providing nutrition to the fetus, stores chemistry for the onset of the labor and protects the supply line. Since 1990, stromal cells, which basically resemble mesenchymal fibroblasts found elsewhere during in utero development, were identified in human WJ. Stemness of these cells has been demonstrated by in vitro differentiation and by the identification of membrane markers specific for MSCs. In veterinary medicine, Mitchell et al. (2003) reported that cells isolated from swine umbilical cord matrix could differentiate in vitro in neuronal-like cells, capable of expressing glial specific proteins; more recently, it has been demonstrated that porcine umbilical cord MSCs resembled pluripotent cells, since they express early transcription factors Oct-4, Sox-2 and Nanog (Carlin et al 2006). Instead, Nanog expression by caprine WJ contradicts data previously obtained in swine: caprine WJ cells showed short doubling time, ability to generate clones and in vitro differentiation capacity, but did not express Nanog gene (Babaei et al 2008). However, in this study, cryopreserved cells were used after thawing for RNA extraction, which may affect Nanog gene expression. In 2007, Hoyonowski et al. demonstrated the presence of MSCs in equine umbilical cord matrix: isolated cells underwent in vitro differentiation and showed expression of embryonic and mesenchymal markers. In our laboratory, fibroblast like cells were observed after culture of equine WJ digested sample; compared with cells isolated from cord blood or amniotic fluid, cultured under the same conditions, cells from WJ expanded more rapidly. After culture in differentiation media, cells stained positive with Alizarin Red, Alcian Blue e Oil Red O staining protocols. Furthermore, the same cells expressed mesenchymal markers such as CD90, CD44, CD105 and were negative for hematopoietic markers. Recently, MSCs were also isolated from canine WJ (Filioli Uranio et al 2011), and Azari et al (2011) demonstrated that MSCs isolated from caprine WJ could be used for regenerative therapy of induced skin wound. In our experience, MSCs isolated from equine WJ can be successfully used in foals with septicemic or decubitus skin wounds. These results demonstrate that equine MSCs from these samples can be induced to form multiple cell types that underlie their value for regenerative medicine in injured horses. Results reported in literature demonstrate that MSCs from domestic animals WJ could be used as a model to study cell biology and have an application in therapeutic programs.