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Abstract

Wound healing is a serious medical concern and the need for a technological method is needed to replace the current methods of wound managing that have not shown any improvement for case numbers, cost and quality of life. Of all the possible technological interventions available, electrical impulses and light irradiations have the most potential for application. Nonetheless, the inconsistent use of parameters, setups and configurations of both has led to confusion in the reporting of results suggesting that a more consistent and rational application of these technical details is still needed.

Therefore, this thesis aims to find the optimal parameters that can inhibit the growth of Escherichia coli (E. Coli) bacteria and facilitate cellular migration, proliferation and the transdifferentiation of the key cell types involved in the wound healing process; fibroblasts and endothelial by investigating the effect of electrobiomodulation (EBM) and photobiomodulation (PBM) separately and combined. It is believed that this combined modality for wound healing is the first reported in the literature and therefore it is introduced as electrophotobiomodulation (EPBM).

For EBM, human dermal fibroblasts (HDF) were treated with a monophasic electric current pulse of 250ms at 300mHz at different intensities of 0μA (control), 50μA, 80μA, 100μA and 200μA for 4 hours. Cell migration and proliferation were measured at 24 and 48 hours postelectrobiomodulation.

For PBM, HDF and human umbilical vein endothelial cells (HUVEC) were treated with blue LED light (420nm) and red LED light (670nm) both at a flounce of 12J/cm2. Cell migration and cell proliferation were measured as above. The antibacterial growth effect was also evaluated with 420nm, 670nm and both combined (420nm+670nm) at a fluence=144J/cm2. The optical density (OD600) of the bacteria was measured during a 4-hour period at 1-hour
intervals post-irradiation.

For EPBM, the 12J/cm2 red light was combined with the 50uA monophasic electrical current pulse of 250ms at 300mHz. Cellular changes were migration as above.

The investigation found 50μA to be the optimum current intensity for inducing cellular changes without thermal effect, cell detachment or apoptotic effects, as was the case in the three other higher intensity groups. At 48 hours, 50μA increased proliferation and migration by 1.6-fold. The 200μA gave an antibacterial growth response with the highest significance at 24 hours.

Red light (670nm) improved the migration proliferation by 1.67-fold, while blue light (420nm) showed an inhibitory effect on bacterial growth with highest significance at 2 hours post-illumination. The combination of 420nm+670nm produced an additional bacteriostatic effect of high significance at 4 hours.

It was found that EPBM did improve the migration rate by 2.2-fold and the proliferation by 1.84-fold, compared to the above-mentioned numbers both EBM and PBM. In addition, further improvements were resulted from using 20%(w/v) gelatine coating.

The research findings confirmed that wound healing can be modulated when using the appropriate parameters. Hence, this novel and pioneering EPBM protocol also produces a positive effect on cell migration and proliferation. In contrast, inappropriate EBM parameters were shown to have a significant effect on cell detachment and apoptotic response resulting from the thermal and cellular effect associated with intensities higher than 50μA.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QH Natural history > QH301 Biology R Medicine > R Medicine (General) T Technology
Departments:	School of Science & Technology > Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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