the presence sellekchem of serum. Yet, serum free conditioned medium Inhibitors,Modulators,Libraries of ADSC resulted in activated STAT3 by 4 fold both under normo ia and hypo ia conditions in serum starved rnCM. The peak of activation of p STAT3 was reached in rnCM by stimulation with conditioned medium of ADSC primed with IL 1B both under normo ia and hyp o ia resulting in respectively 8. 5 and 10 fold increase compared to the serum free controls. In rnCM Erk1 2 was strongly phosphorylated in the presence of serum. Under serum free condition the phosphorylation of Erk1 2 was 2 fold decreased compared to serum Inhibitors,Modulators,Libraries control. The stimulation Inhibitors,Modulators,Libraries of rnCM with the serum free conditioned medium of ADSC and the IL 1B primed conditioned medium of ADSC resulted in the strong ac tivation of Erk1 2, reaching 1.

5 fold increase in compare to serum free controls both under normo ia and hypo ia. The activation of Erk1 2 in rnCM by the serum free conditioned medium of ADSC was comparable to the level of phosphorylation in the rnCM stimulated with serum. Inhibitors,Modulators,Libraries In HL 1 cardiomyocytes, STAT3 and Erk1 2 were both phosphorylated in the presence of serum. After 24h of serum deprivation, the phosphorylation i. e. activation, of these transcription factors was only slightly reduced. The phosphorylation of STAT3 was decreased by 3 fold in the presence of the p STAT3 inhibitor, while Erk1 2 phosphorylation was reduced by 8 and 4 fold with the MEK inhibitor respectively in compare to the serum and serum free controls. Remarkably, stimulation of HL 1 cardiomyocytes with serum free IL 1B stimulated ADSC conditioned medium resulted in a 2 fold increase in phosphorylation of STAT3 and Erk1 2, that reached higher level than serum controls.

Blocking of STAT3 phosphorylation resulted in reduced levels of phosphorylated STAT3 and 2 fold increased phosphoryl ation of Erk1 2. In contrast, activation of phosphorylated STAT3 did not depend on activation of Erk1 2 phosphorylation. Simultaneous inhibition of JAK STAT and MAPK signaling pathway resulted in AV-951 reduced levels of phosphorylated STAT3 by 2. 7 fold and phosphorylated Erk1 2 by 2 fold. ADSC dependent signaling pathways targeting HL 1 cardiomyocyte proliferation rate In the presence of mitogenic factors such as serum and conditioned medium of ADSC, HL 1 cardiomyocytes showed an increase in proliferation.

In the presence of serum addition of inhibitors targeting example upstream or downstream of JAK STAT and MAPK signaling pathway resulted in a decreased proliferation rate of HL 1 cardiomyocytes ranging from 31 to 41%. Pre treatment of HL 1 cardiomyocytes with these inhibi tors also reduced the mitogenic effect of conditioned medium of ADSC, observed as a significant decrease in the fraction of BrdUrd positive cells by 24 to 37%. Discussion In this study we show that Adipose Derived Stromal Cells enhance the proliferation rate of both pri mary CM and a CM cell line, in a paracrine manner and in direct co culture in vitro. One of the main stimulators secreted by ADSC was IL 6. The in vitro hyp