The aim of this study was to investigate the immunogenicity of human umbilical cord mesenchymal stem cells (hUCMSCs) cultured in vitro by detecting changes in major histocompatibility complex expression. Major histocompatibility complex expression was detected by RT&ndash;PCR and flow cytometry. Morphologically, hUCMSCs exhibited no visible changes before the 5 st passage of the in vitro culture. In addition, At the molecular level, the cells continued expressing the specific positive surface markers, CD105, CD73 and CD90, and did not express the negative surface markers, CD14, CD34 or CD45, during culture ex vivo. Furthermore, the hUCMSCs exhibited low immunogenicity, which was maintained when cultured for five passages. Taken as a whole, these results suggested that hUCMSCs cultured in vitro may be safely for transplanted because of low immunogenicity before the fifth passage.&nbsp;

Immunogenicity of human umbilical cord mesenchymal&nbsp;stem cells during ex vivo expansion

Background: Immunophenotyping has been proven a valuable tool in diagnostic and research immunology laboratories to evaluate the immune status in health and disease. However, in some cases, cells cannot be analyzed immediately after separation and must be stored for later analysis. The present study was undertaken to investigate the impact of cryopreservation of camel PBMC on their vitality, recovery, shape, staining patterns with monoclonal antibodies and lymphocyte composition. 
&nbsp; 
Methods: Flow cytometry was employed to analyze cell apoptosis, necrosis, shape change, staining patterns with mAbs and cellular composition of freshly separated and cryopreserved camel PBMC. 
&nbsp; 
Result: The results showed similar lymphocytes and monocytes absolute numbers with comparable percentages of apoptotic and necrotic cells between fresh and preserved PBMC indicating no significant impact of cryopreservation on the recovery of camel PBMC. Although a cryopreservation-induced shape change was identified for camel lymphocytes, this change did not interfere with the identification of cryopreserved lymphocytes based on their SSC and FSC characteristics. In addition, the reactivity of camel PBMC with mAbs to the cell markers antigens CD45, CD44, CD11a, MHC-I, CD14, CD163 and CD172a remained unchanged for cryopreserved cells. However, mAbs to MHC-II and BAQ44A displayed modified binding to cryopreserved PBMC leading to significant changes in the positively stained B cells and increased MHC-II expression on monocytes. In conclusion, the results of the current study show that storing camel PBMC in cryopreservation media at -80 is an appropriate procedure for preserving the epitopes for all the used mAbs with modified binding to B cell markers.

Flow Cytometric Assessment of the Influence of Cryopreservation on Vitality, Recovery and Immunophenotype of Camel Peripheral Blood Mononuclear Cells

Immunogenicity of human umbilical cord mesenchymal stem cells during ex vivo expansion

Flow Cytometric Assessment of the Influence of Cryopreservation on Vitality, Recovery and Immunophenotype of Camel Peripheral Blood Mononuclear Cells