Low-level laser therapy for treatment of severe acute respiratory syndrome 2 infection

Abstract

SARS-CoV-2 is a new threat to public health due to its increased transmissibility and immune evasion. Angiotensinconverting enzyme 2 (ACE2) plays a critical role in SARS-CoV-2 infection as its serve as the virus's major entry receptor in humans. Vaccines have been authorized for emergency use to control the current pandemic and they have greatly reduced the spread of SARS-CoV-2 and mortality rates, nevertheless this coronavirus has shown the ability to endure crucial mutations that increases its infectivity which makes it likely that the virus will continue to mutate and disseminate. There is a need to find and introduce alternative and effective methods of controlling SARS-CoV-2. Notably, low-level laser therapy (LLLT) is a method of exposing cells or tissue to low levels of red and near infrared light which has a high success rate for treatment of other ailments. The aim of the study is to determine for the first time, the effects of LLLT on SARS-CoV-2 infected HEK293/ACE2 cells and compare them to uninfected ones. Both infected and uninfected HEK293/ACE2 cells were irradiated at a wavelength of 640 nm, at different doses. Then, the effects of laser irradiation on the cells and the virus were evaluated using luciferase, cytotoxicity, and cell viability assays. Preliminary results showed that irradiated uninfected cells had no changes in cell viability and cytotoxicity, while there were changes in irradiated infected cells. In addition, laser irradiation caused cell membrane damage in infected cells. Lastly, uninfected irradiated cells showed no luciferase activity while laser irradiation reduced luciferase activity in infected cells.

The effect of low-level laser therapy on severe acute respiratory syndrome coronavirus-2 infected cells

“…The proliferation of both infected and uninfected cells irradiated at 10 J/cm² showed a great decrease when compared to the positive and negative controls respectively (P< 0.05), suggesting that laser irradiation at high fluences leads to a decline in the growth of cells. All the results obtained in this MTT assay correlate to the cell viability assay results obtained from the previous publication [10]. As demonstrated in Figure 3.2, all the uninfected cells had high TAC levels compared to the infected cells.…”

“…Our earlier publication [10] explained the SARS-CoV-2 pseudovirus production process. In summary, two plasmids, the backbone pNL4.luc plasmid and the SARS-CoV-2 ancestral variant spike (D614G) spike plasmid were cotransfected into HEK293 cells.…”

“…For chemical cytotoxicity testing and drug screening, in vitro cell viability and cytotoxicity assays using cultured cells are commonly employed. In our previous study, it was observed that LLLT led to the reduction of SARS-CoV-2 infection in HEK293/ACE2 cells irradiated at a fluence of 8 J/cm² [10], and in the current study, we want to link the biological assay's results that will be obtained from the current study with the results that were obtained from the previous study. The aim of this study is to investigate the effect of LLLT on SARS-CoV-2-infected HEK293/ACE2 cells using biological assays, including MTT assay, cell viability live/dead, green/deep red assay, and reactive oxygen species (ROS).…”

HEK293/ACE2 cells' response to severe acute respiratory syndrome coronavirus-2 infection and low-level-laser therapy under microscopy

“…A growth medium Dulbecco's Modified Eagle Medium (DMEM) containing 10% fetal bovine serum and 0.15% L-Glutamine-Penicillin-Streptomycin was used for both cell lines. The cell lines were kept in a cell culture incubator operating at 37° C [8].…”

“…The production of SARS-CoV-2 pseudovirus has been previously described in our previously published article [9]. Briefly HEK293T cells were co-transfected with two plasmids, a SARS-CoV-2 ancestral variant spike (D614G) spike plasmid, and a backbone pNL4.luc plasmid.…”