Enhanced angiogenesis in grafted skins by laser-induced stress wave-assisted gene transfer of hepatocyte growth factor

Comparison of carboxy therapy and fractional Q-switched ND:YAG laser on periorbital dark circles treatment: a clinical trial

Treatment of the periorbital dark circles (PDCs) is a current challenge, with most treatment methods failing to yield promising results. The effectiveness of two common methods for periorbital dark circle treatment was compared in 28 patients with PDC. The patients were randomly divided into two groups of equal numbers: the first group received carboxy therapy, and the second group fractional 10,64 nm Q-switched Nd:YAG laser. In the carboxy therapy group, the treatment was performed six times, with 1-week intervals between sessions. In the group treated by Nd:YAG laser, the treatment was conducted in four sessions, with 1-month intervals between sessions. The results were evaluated through biometric evaluation, scoring on the visual analog scale (VAS) by both physicians and patients, and patients' satisfaction. Side effects of the treatments were also evaluated. The results showed that both carboxy therapy and Nd:YAG laser are effective in the treatment of periorbital dark circles, but carboxy therapy is significantly more effective. An increase in the skin lightness and a decrease in the melanin content of the periorbital skin was observed in the group receiving carboxy therapy, and these changes were more pronounced in this group compared to the group of Nd:YAG laser. In addition, side effects, such as erythema and post-inflammatory hyperpigmentation, were less in carboxy therapy than in Nd:YAG laser. Furthermore, the procedure was less expensive and easier to perform compared to Nd:YAG laser. Carboxy therapy is significantly more effective than Nd:YAG laser in PDC treatment.Trial registration: IRCT20080901001159N24.

Laser-assisted nucleic acid delivery: A systematic review

Gene therapy has become an effective treatment modality for some conditions. Laser light may augment or enhance gene therapy through photomechanical, photothermal, and photochemical. This review examined the evidence base for laser therapy to enhance nucleic acid transfection in mammalian cells. An electronic search of MEDLINE, Scopus, EMBASE, Web of Science, and Google Scholar was performed, covering all available years. The preferred reporting items for systematic reviews and meta-analyses guideline for systematic reviews was used for designing the study and analyzing the results. In total, 49 studies of laser irradiation for nucleic acid delivery were included. Key approaches were optoporation, photomechanical gene transfection, and photochemical internalization. Optoporation is better suited to cells in culture, photomechanical and photochemical approaches appear well suited to in vivo use. Additional studies explored the impact of photothermal for enhancing gene transfection. Each approach has merits and limitations. Augmenting nucleic acid delivery using laser irradiation is a promising method for improving gene therapy. Laser protocols can be non-invasive because of the penetration of desirable wavelengths of light, but it depends on various parameters such as power density, treatment duration, irradiation mode, etc. The current protocols show low efficiency, and there is a need for further work to optimize irradiation parameters.

Characterization of the cellular response triggered by gold nanoparticle-mediated laser manipulation

Laser-based transfection techniques have proven high applicability in several cell biologic applications. The delivery of different molecules using these techniques has been extensively investigated. In particular, new high-throughput approaches such as gold nanoparticle–mediated laser transfection allow efficient delivery of antisense molecules or proteins into cells preserving high cell viabilities. However, the cellular response to the perforation procedure is not well understood. We herein analyzed the perforation kinetics of single cells during resonant gold nanoparticle–mediated laser manipulation with an 850-ps laser system at a wavelength of 532 nm. Inflow velocity of propidium iodide into manipulated cells reached a maximum within a few seconds. Experiments based on the inflow of FM4-64 indicated that the membrane remains permeable for a few minutes for small molecules. To further characterize the cellular response postmanipulation, we analyzed levels of oxidative heat or general stress. Although we observed an increased formation of reactive oxygen species by an increase of dichlorofluorescein fluorescence, heat shock protein 70 was not upregulated in laser-treated cells. Additionally, no evidence of stress granule formation was visible by immunofluorescence staining. The data provided in this study help to identify the cellular reactions to gold nanoparticle–mediated laser manipulation.

Photomechanical wave-driven delivery of siRNAs targeting intermediate filament proteins promotes functional recovery after spinal cord injury in rats

The formation of glial scars after spinal cord injury (SCI) is one of the factors inhibiting axonal regeneration. Glial scars are mainly composed of reactive astrocytes overexpressing intermediate filament (IF) proteins such as glial fibrillary acidic protein (GFAP) and vimentin. In the current study, we delivered small interfering RNAs (siRNAs) targeting these IF proteins to SCI model rats using photomechanical waves (PMWs), and examined the restoration of motor function in the rats. PMWs are generated by irradiating a light-absorbing material with 532-nm nanosecond laser pulses from a Q-switched Nd:YAG laser. PMWs can site-selectively increase the permeability of the cell membrane for molecular delivery. Rat spinal cord was injured using a weight-drop device and the siRNA(s) solutions were intrathecally injected into the vicinity of the exposed SCI, to which PMWs were applied. We first confirmed the substantial uptake of fluorescence-labeled siRNA by deep glial cells; then we delivered siRNAs targeting GFAP and vimentin into the lesion. The treatment led to a significant improvement in locomotive function from five days post-injury in rats that underwent PMW-mediated siRNA delivery. This was attributable to the moderate silencing of the IF proteins and the subsequent decrease in the cavity area in the injured spinal tissue.

Propagation characteristics of photomechanical waves and their application to gene delivery into deep tissue

Targeted gene transfection can be achieved by the use of photomechanical waves (PMWs) generated by irradiating a solid material with high-power nanosecond laser pulses. To examine the treatable tissue depth, we investigated propagation characteristics of PMWs and depth-dependent properties of gene transfection with different laser fluences and spot diameters. Pressure characteristics of PMWs were measured at different propagation distances using tissue phantoms and their propagation was imaged by shadowgraphing. Phantoms with various thicknesses were placed on rat dorsal skin that had been injected with plasmid DNA coding for a reporter gene and three pulses of PMWs were applied from the top of each phantom. Significant gene expression was observed in the skin even under a 15-mm-thick tissue phantom and the depth-dependent relationships between PMW parameters and gene expression level were revealed. The data obtained will be useful for determining appropriate laser parameters for PMW-based gene transfer into deep-located tissue.

Site-specific gene transfer into the rat spinal cord by photomechanical waves

Nonviral, site-specific gene delivery to deep tissue is required for gene therapy of a spinal cord injury. However, an efficient method satisfying these requirements has not been established. This study demonstrates efficient and targeted gene transfer into the spinal cord by using photomechanical waves (PMWs), which were generated by irradiating a black laser absorbing rubber with 532-nm nanosecond Nd:YAG laser pulses. After a solution of plasmid DNA coding for enhanced green fluorescent protein (EGFP) or luciferase was intraparenchymally injected into the spinal cord, PMWs were applied to the target site. In the PMW application group, we observed significant EGFP gene expression in the white matter and remarkably high luciferase activity only in the spinal cord segment exposed to the PMWs. We also assessed hind limb movements 24 h after the application of PMWs based on the Basso-Beattie-Bresnahan (BBB) score to evaluate the noninvasiveness of this method. Locomotor evaluation showed no significant decrease in BBB score under optimum laser irradiation conditions. These findings demonstrated that exogenous genes can be efficiently and site-selectively delivered into the spinal cord by applying PMWs without significant locomotive damage.

Targeted gene transfer into rat facial muscles by nanosecond pulsed laser-induced stress waves

We investigate the feasibility of using nanosecond pulsed laser-induced stress waves (LISWs) for gene transfer into rat facial muscles. LISWs are generated by irradiating a black natural rubber disk placed on the target tissue with nanosecond pulsed laser light from the second harmonics (532 nm) of a Q-switched Nd:YAG laser, which is widely used in head and neck surgery and proven to be safe. After injection of plasmid deoxyribose nucleic acid (DNA) coding for Lac Z into rat facial muscles, pulsed laser is used to irradiate the laser target on the skin surface without incision or exposure of muscles. Lac Z expression is detected by X-gal staining of excised rat facial skin and muscles. Strong Lac Z expression is observed seven days after gene transfer, and sustained for up to 14 days. Gene transfer is achieved in facial muscles several millimeters deep from the surface. Gene expression is localized to the tissue exposed to LISWs. No tissue damage from LISWs is observed. LISW is a promising nonviral target gene transfer method because of its high spatial controllability, easy applicability, and minimal invasiveness. Gene transfer using LISW to produce therapeutic proteins such as growth factors could be used to treat nerve injury and paralysis.

Accelerated adhesion of grafted skin by laser-induced stress wave-based gene transfer of hepatocyte growth factor

Gene therapy using wound healing-associated growth factor gene has received much attention as a new strategy for improving the outcome of tissue transplantation. We delivered plasmid DNA coding for human hepatocyte growth factor (hHGF) to rat free skin grafts by the use of laser-induced stress waves (LISWs); autografting was performed with the grafts. Systematic analysis was conducted to evaluate the adhesion properties of the grafted tissue; angiogenesis, cell proliferation, and reepithelialization were assessed by immunohistochemistry, and reperfusion was measured by laser Doppler imaging as a function of time after grafting. Both the level of angiogenesis on day 3 after grafting and the increased ratio of blood flow on day 4 to that on day 3 were significantly higher than those in five control groups: grafting with hHGF gene injection alone, grafting with control plasmid vector injection alone, grafting with LISW application alone, grafting with LISW application after control plasmid vector injection, and normal grafting. Reepithelialization was almost completed on day 7 even at the center of the graft with LISW application after hHGF gene injection, while it was not for the grafts of the five control groups. These findings demonstrate the validity of our LISW-based HGF gene transfection to accelerate the adhesion of grafted skins.

Photoacoustic monitoring of burn healing process in rats

We performed multiwavelength photoacoustic (PA) measurement for extensive deep dermal burns in rats to monitor the healing process of the wounds. The PA signal peak at 532 nm, an isosbestic point for oxyhemoglobin (HbO(2)) and deoxyhemoglobin (HHb), was found to shift to a shallower region of the injured skin tissue with the elapse of time. The results of histological analysis showed that the shift of the PA signal reflected angiogenesis in the wounds. Until 24 h postburn, PA signal amplitude generally increased at all wavelengths. We speculate that this increase in amplitude is associated with dilation of blood vessels within healthy tissue under the injured tissue layer and increased hematocrit value due to development of edema. From 24 to 48 h postburn, the PA signal showed wavelength-dependent behaviors; signal amplitudes at 532, 556, and 576 nm continued to increase, while amplitude at 600 nm, an HHb absorption-dominant wavelength, decreased. This seems to reflect change from shock phase to hyperdynamic state in the rat; in the hyperdynamic state, cardiac output and oxygen consumption increased considerably. These findings show that multiwavelength PA measurement would be useful for monitoring recovery of perfusion and change in local hemodynamics in the healing process of burns.