THE EFFECT OF STEM CELLS AS AN ADJUVANT ON THE IMMUNOGENICITY OF A POTENTIAL ANTI-SCHISTOSOMAL VACCINE IN MICE.

Vaccination against schistosomes can be targeted towards the prevention of infection and/or to the reduction of parasite fecundity and pathology. However, as eggs are responsible mainly for schistosomiasis pathology, so crude soluble egg antigen (SEA) seems suitable to be used as a potential vaccine. Many studies have provided new insights establishing a role for mesenchymal stem cells (MSCs) in liver regeneration and improvement of schistosomiasis hepatic fibrosis, in addition to the need for standardized and effective adjuvant-vaccine formulations. So, the aim of this work is to evaluate the effect of stem cells when used as an adjuvant of a potential anti-schistosomal vaccine (crude SEA) in murine models. The current work was carried out on 100 mice (30 males for harvesting MSCs + 70 females for seven study groups, each of 10). A schedule of vaccination and challenge infection was followed so, GI (control healthy), G2 (control infected only) infected subcutaneously with S. mansoni cercaria (80-90 Schistosoma mansoni cercariae suspended in 0.2 ml distilled Water), G 3 (FCA then infected) received Freund's complete adjuvant (FCA) then infected, G4 (MSCs then infected) received MSCs then infected, G5 (SEA then infected) received SEA vaccine then infected, G6 (SEA+FCA then infected) received SEA vaccine and FCA then infected, G7 (SEA+MSCs then infected) received SEA vaccine and MSCs then infected. The current work was assessed by histopathological study and morphometric analysis (using H&E and Masson's Trichrome stains) to highlight number, size and type of liver granulomas and percentage of liver fibrosis, immunological and molecular studies (RNA extraction, Re- verse Transcriptase and PCR technique) for detection of interleukin-10 mRNA gene expression in liver tissue by reverse transcriptase & polymerase chain reaction (RT & PCR). The results showed that a- SEA alone as a potential anti-schistosomal vaccine was more or less moderately protective, b- MSCs alone before the infection had mild prophylactic effects, c- MSCs as an adjuvant of the crude SEA increased its capabilities with highly significant results regarding the decrease in granuloma number, size, percentage and density of hepatic fi- brosis, and d-There was significant increase in IL-10 mRNA gene expression on using (SEA+MSCs) (G7) if compared to other tested groups.