Abstract
M. Tech.
Phototobiomodulation (PBM), also known as low level laser therapy
(LLLT) or photobiostimulation, is a non-invasive form of therapy that
utilizes low intensity laser light or irradiation to provide healing. However,
in order for healing to be successful certain laser parameters need to be
taken into consideration i.e. fluence (dosage), wavelength and power
density. Laser therapy has been used for various medical applications and
fields.
Multiple cytokines and growth factors are involved in wound healing
including Interleukin (IL)-1, IL-6 and Tumour Necrosis Factor alpha (TNF-
a). In diseased state(s) such as diabetes mellitus (DM) or psoriasis, these
growth factors or cytokines are either found elevated or decreased
depending on various factors and for abnormally prolonged periods.
However, inflammatory cytokines are usually elevated. Phototherapy has
been reported to accelerate wound healing, attenuate pain and cease
inflammation. However, the effect of phototherapy on cytokine modulation
has not been explored extensively, especially under various stress
mechanisms. Furthermore, the pathway that laser irradiation induces on
modulated pro-inflammatory cytokines has not been clearly elucidated as
scientists typically report on the up- or down-regulated expression of
cytokines.
Numerous authors have reported on the efficacy of laser irradiation to
enhance the rate of wound healing and proliferation in normal and diabetic
cells or tissue; however, literature that has demonstrated the latter on
hypoxic insulted cells is inadequate. In this study hypoxic insult was
induced as it is one of the factors that usually prolong the healing process
in diabetic wounds. Prior to commencing with the main study, a pilot study
was done to exclude the effect of osmotic pressure on cells grown in
media containing additional glucose, and thus simulating a diabetic model
iv
in vitro. Mannitol was used as a control since it is not absorbed by the
cells. The study involved four groups namely: normal, normal wounded,
mannitol wounded and diabetic wounded cells with each group having a
non-irradiated control. Mannitol wounded and diabetic wounded cells had
a final concentration of 30 mM mannitol and glucose respectively. A
wavelength of 636 nm at a fluence of 5 J/cm2 was used on day 1;
experiments were repeated four times and all tests were done in duplicate.
Cellular responses (Trypan Blue, adenosine triphosphate (ATP) and
lactate dehydrogenase (LDH)) and morphological changes were assessed
after 1 h incubation post-irradiation in both irradiated and non-irradiated
cultures.