Objective: This study aims to explore the potential effects and mechanisms of heat shock pretreatment (HSP) on bone marrow mesenchymal stem cells (BMSCs) in chemotherapy microenvironment. Methods: The optimal condition of HSP was identified. Cisplatin was added to the heat shock pretreated bone marrow mesenchymal stem cells (HS-MSCs) medium to simulate the chemotherapy microenvironment. The effect of HSP on the biological characteristics of HS-MSCs was explored. The proliferation of BMSCs was detected by CCK-8 assay

the viability was measured by Hoechst33342/PI

and the apoptosis was detected by flow cytometry. The potential mechanisms of HSP were further explored from the perspective of heat shock proteins and autophagy. The expression of heat shock protein 70 (Hsp70)

Hsp90

Beclin1 and LC3B after HSP were detected by Western blot. The number of autophagosomes was observed by transmission electron microscopy. Results: In simulated chemotherapy microenvironment

the apoptosis rate of heat shock model group was lower than that of model group. In addition

the proliferation rate of the heat shock model group was higher than that of the model group

while the ratio of bright blue/dark red fluorescence cells was lower than that of the model group. The expressions of Hsp70 and Hsp90 were significantly up-regulated with time and reached the peak at 48 hours after HSP. Meanwhile

the number of autophagosomes

the expression of Beclin1 and the ratio of LC3BⅡ/LC3BⅠwere all decreased after HSP.Conclusion: HSP can improve the viability and anti-apoptosis ability of BMSCs under the chemotherapy microenvironment

and its effect may be related to the enhancement of Hsp70 and Hsp90 expressions and the weakening of autophagy level.