Objective: The biological action of a modulated low energy red end laser light has been investigated to develop an improved level of understanding regarding the potential clinical use of Human Very Small Embryonic-Like Stem Cells (hVSEL) in regenerative medicine.

Materials and Methods: hVSEL stem cells were confirmed to exist in the platelet compartment of the platelet rich plasma (PRP) fraction of normal peripheral blood obtained from National Health Service Blood and Transfusion (NHSBT).

Results: hVSEL stem cell proliferation was identified in PRP using flow cytometry for the surface antigens known to be expressed by hVSEL stem cells (Oct 3/4, SSEA4 and CXCR4) in the lineage negative (Lin-) compartment. The experiments confirm the presence of hVSEL stem cells in PRP which were then exposed to a SONG modulated 5 mW, 670 nm red laser light, adjusted through optical phase conjugation to 1 mW output for 3 minutes and with variations in modulation and laser exposure times. The resultant laser exposed hVSEL stem cells were then re-assessed for cell proliferation using flow cytometry. Those hVSEL stem cells exposed to laser light were shown to have an increase in hVSEL stem cell proliferation compared to controls.

Conclusions: This is the first report of hVSEL stem cell proliferation in response to modulated laser light.