Highlights

Cp lysates (CpL) improved cell viability of irradiated normal cells in vitro.

CpL exhibited radiation-induced ROS scavenging activity.

CpL reduced γH2AX, Rad51 and pDNA-PKcs expression in irradiated normal cells.

CpL reduced the number of γH2AX positive cells in 10 Gy irradiated 3D skin tissue.

CpL-S (<10 kDa) displayed better radioprotective activity than CpL-B (>10 kDa).

Abstract

Two fractions, small and big (CpL-S, CpL-B), from Cryptosporidium parvum lysate (CpL) were prepared and its radioprotective activity was evaluated on normal cells. Both fractions improved cell viability of normal cells in a dose-dependent manner. 20 μg CpL-S and CpL-B improved cell viability of 10 Gy irradiated COS-7 cells by 38% and 34% respectively, while in HaCat cells 16% and 18% improved cell viability was observed, respectively. CpL-S scavenged IR-induced ROS more effectively compared to the CpL-B, 50% more in COS-7 cells and 15% more in HaCat cells. There was a significant reduction of γH2AX, Rad51, and pDNA-PKcs foci in CpL-S treated cells compared to control or CpL-B group at an early time point as well as late time point. In 3D skin tissue, CpL-S reduced the number of γH2AX positive cells by 31%, compared to control, while CpL-B reduced by 9% (p < 0.005) at 1 h post 10 Gy irradiation and 22% vs 6% at 24 h post-IR (p < 0.005). Taken together, CpL-S significantly improved cell viability and prevented radiation-induced DNA damage in normal cells as well as 3D skin tissues by effectively scavenging ROS generated by ionizing radiation. CpL-S can be a candidate for radioprotector development.