1. Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan;
2. Bachelor Program of Senior Services, Southern Taiwan University of Science and Technology, Tainan, Taiwan;
3. Department of Medical Applied Chemistry, College of Health Care and Management, Chung Shan Medical University, Taichung, Taiwan;
4. Graduate Institute of Chinese Medical Science, School of Chinese Medicine, China Medical University, Taichung, Taiwan;
5. Department of Health and Nutrition Biotechnology, Asia University, Taichung, Taiwan;
6. Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan;
7. Center for Molecular Medicine, China Medical University Hospital, Taichung, Taiwan.
* These authors contributed equally to this work
Objectives: Cell transplantation therapy of Schwann cells (SCs) is a promising therapeutic strategy after spinal cord injury. However, challenges such as oxidative stress hinder satisfactory cell viability and intervention for enhancing SCs survival is critical throughout the transplantation procedures. Ocimum gratissimum, widely used as a folk medicine in many countries, has therapeutic and anti-oxidative properties and may protect SCs survival.
Methods: We examined the protective effects of aqueous O. gratissimum extract (OGE) against cell damage caused by H2O2-induced oxidative stress in RSC96 Schwann cells.
Results: Our results showed that the RSC96 cells, damaged by H2O2 oxidative stress, decreased their viability up to 32% after treatment with different concentrations of up to 300 μM H2O2, but OGE pretreatment (150 or 200 μg/mL) increased cell viability by approximately 62% or 66%, respectively. Cell cycle analysis indicated a high (43%) sub-G1 cell population in the H2O2-treated RSC96 cells compared with untreated cells (1%); whereas OGE pretreatment (150 and 200 μg/mL) of RSC96 cells significantly reduced the sub-G1 cells (7% and 8%, respectively). Furthermore, Western blot analysis revealed that OGE pretreatment inhibited H2O2-induced apoptotic protein caspase-3 activation and PARP cleavage, as well as it reversed Bax up-regulation and Bcl-2 down-regulation. The amelioration of OGE of cell stress and stress-induced apoptosis was proved by the HSP70 and HSP72 decrease.
Conclusion: Our data suggest that OGE may minimize the cytotoxic effects of H2O2-induced SCs apoptosis by modulating the apoptotic pathway and could potentially supplement cell transplantation therapy.
Keywords: Ocimum gratissimum, Schwann cells, oxidative stress, apoptosis.