Photobiomodulation of human osteoblast-like cells in vitro by low-intensity-pulsed LED light

Photobiomodulation: a novel approach to promote trans-differentiation of adipose-derived stem cells into neuronal-like cells

JOURNAL/nrgr/04.03/01300535-202502000-00035/figure1/v/2024-05-28T214302Z/r/image-tiff Photobiomodulation, originally used red and near-infrared lasers, can alter cellular metabolism. It has been demonstrated that the visible spectrum at 451-540 nm does not necessarily increase cell proliferation, near-infrared light promotes adipose stem cell proliferation and affects adipose stem cell migration, which is necessary for the cells homing to the site of injury. In this in vitro study, we explored the potential of adipose-derived stem cells to differentiate into neurons for future translational regenerative treatments in neurodegenerative disorders and brain injuries. We investigated the effects of various biological and chemical inducers on trans-differentiation and evaluated the impact of photobiomodulation using 825 nm near-infrared and 525 nm green laser light at 5 J/cm2. As adipose-derived stem cells can be used in autologous grafting and photobiomodulation has been shown to have biostimulatory effects. Our findings reveal that adipose-derived stem cells can indeed trans-differentiate into neuronal cells when exposed to inducers, with pre-induced cells exhibiting higher rates of proliferation and trans-differentiation compared with the control group. Interestingly, green laser light stimulation led to notable morphological changes indicative of enhanced trans-differentiation, while near-infrared photobiomodulation notably increased the expression of neuronal markers. Through biochemical analysis and enzyme-linked immunosorbent assays, we observed marked improvements in viability, proliferation, membrane permeability, and mitochondrial membrane potential, as well as increased protein levels of neuron-specific enolase and ciliary neurotrophic factor. Overall, our results demonstrate the efficacy of photobiomodulation in enhancing the trans-differentiation ability of adipose-derived stem cells, offering promising prospects for their use in regenerative medicine for neurodegenerative disorders and brain injuries.

The role of photobiomodulation in accelerating bone repair

Bone repair is faced with obstacles such as slow repair rates and limited bone regeneration capacity. Delayed healing even nonunion could occur in bone defects, influencing the life quality of patients severely. Photobiomodulation (PBM) utilizes different light sources to derive beneficial therapeutic effects with the advantage of being non-invasive and painless, providing a promising strategy for accelerating bone repair. In this review, we summarize the parameters, mechanisms, and effects of PBM regulating bone repair, and further conclude the current clinical application of PBM devices in bone repair. The wavelength of 635-980 nm, the output power of 40-100 mW, and the energy density of less than 100 J/cm2 are the most commonly used parameters. New technologies, including needle systems and biocompatible and implantable optical fibers, offer references to realize an efficient and safe strategy for bone repair. Further research is required to establish the reliability of outcomes from in vivo and in vitro studies and to standardize clinical trial protocols.

Periodontal Disease Monitoring by Raman Spectroscopy of Phosphates: New Insights into Pyrophosphate Activity

(1) Background: The intent of this survey was to investigate the quality of the alveolar bone by revealing the different phases for calcified tissues independent of the medical history of the patient in relation to periodontal disease by means of Raman spectroscopy and then to correlate the results by suggesting a possible mechanism for the medical impairment; (2) Methods: The investigation was mainly based on Raman spectroscopy that was performed in vivo during surgery for the selected group of patients. The targeted peaks for the Raman spectra were according to the reference compounds (e.g., calcium phosphates, other phosphates); (3) Results: The variation in the intensity of the spectrum correlated to the specific bone constituents' concentrations highlights the bone quality, while some compounds (such as pyrophosphate, PPi) are strongly related to the patient's medical status, and they provide information regarding a physiological process that occurred in the calcified tissues. Moreover, bone sample fluorescence is related to the collagen (Col) content, enabling a complete evaluation of bone quality, revealing the importance of collagen matrix acting as a load-bearing element for Calcium phosphate (CaP) deposition during the complex bone mineralization process; (4) Conclusions: We highlight that Raman spectroscopy can be considered a viable investigative method for in vivo and rapid bone quality valuation through oral health monitoring.

Effects of Laser Application on Alveolar Bone Mesenchymal Stem Cells and Osteoblasts: An In Vitro Study

Mesenchymal stem cells isolated from the bone marrow have a great differentiation potential, being able to produce many cell lines, including osteoblasts. Osteoblasts have an important role in bone remodeling by actively participating in the maturation and mineralization of the extracellular matrix. The aim of this study was to determine the effect of laser application on the viability and proliferation of osteoblasts. Methods: Alveolar bone was harvested from 8 patients and placed into a culture medium to induce proliferation of mesenchymal stem cells. These were differentiated into osteoblasts in special conditions. The cells from each patient were split into two groups, one was treated using a 980 nm laser (1W output power, pulsed mode, 20 s, 50 mm distance) (laser “+”) and the other one did not receive laser stimulation (laser “-”). Results: Using the confocal microscope, we determined that the cells from the laser “+” group were more active when compared to the laser “-” group. The number of cells in the laser “+” group was significantly greater compared to the laser “-” group as the ImageJ-NIH software showed (p = 0.0072). Conclusions: Laser application increases the proliferation rate of osteoblasts and intensifies their cellular activity.

Selection of a suitable photosynthetically active microalgae strain for the co-cultivation with mammalian cells

Preventing hypoxic zones in 3D bioprinted mammalian cell-laden constructs using an internal oxygen supply could enable a more successful cultivation both in vitro and in vivo. In this study, the suitability of green microalgae as photosynthetic oxygen generators within bioprinted constructs was evaluated by defining and investigating important parameters for a successful co-culture. First, we assessed the impact of light–necessary for photosynthesis–on two non-light adapted mammalian cell types and defined red-light illumination and a temperature of 37°C as essential factors in a co-culture. The four thermotolerant microalgae strains Chlorella sorokiniana, Coelastrella oocystiformis, Coelastrella striolata, and Scenedesmus sp. were cultured both in suspension culture and 3D bioprinted constructs to assess viability and photosynthetic activity under these defined co-culture conditions. Scenedesmus sp. proved to be performing best under red light and 37°C as well as immobilized in a bioprinted hydrogel based on alginate. Moreover, the presence of the antibiotic ampicillin and the organic carbon-source glucose, both required for mammalian cell cultures, had no impact on bioprinted Scenedesmus sp. cultures regarding growth, viability, and photosynthetic activity. This study is the first to investigate the influence of mammalian cell requirements on the metabolism and photosynthetic ability of different microalgal strains. In a co-culture, the strain Scenedesmus sp. could provide a stable oxygenation that ensures the functionality of the mammalian cells.

Promoting Immortalized Adipose-Derived Stem Cell Transdifferentiation and Proliferation into Neuronal-Like Cells through Consecutive 525 nm and 825 nm Photobiomodulation

Neuronal cells can be generated from adipose-derived stem cells (ADSCs) through biological or chemical inducers. Research has shown that this process may be optimized by the introduction of laser irradiation in the form of photobiomodulation (PBM) to cells. This in vitro study is aimed at generating neuronal-like cells with inducers, chemical or biological, and at furthermore treating these transdifferentiating cells with consecutive PBM of a 525 nm green (G) laser and 825 nm near-infrared (NIR) laser light with a fluence of 10 J/cm². Cells were exposed to induction type 1 (IT1): 3-isobutyl-1-methylxanthine (IBMX) (0.5 mM)+indomethacin (200 μM)+insulin (5 μg/ml) for 14 days, preinduced with β-mercaptoethanol (BME) (1 mM) for two days, and then incubated with IT2: β-hydroxyanisole (BHA) (100 μM)+retinoic acid (RA) (10-6 M)+epidermal growth factor (EGF) (10 ng/ml)+basic fibroblast growth factor (bFGF) (10 ng/ml) for 14 days and preinduced with β-mercaptoethanol (BME) (1 mM) for two days and then incubated with indomethacin (200 μM)+RA (1 μM)+forskolin (10 μM) for 14 days. The results were evaluated through morphological observations, viability, proliferation, and migration studies, 24 h, 48 h, and 7 days post-PBM. The protein detection of an early neuronal marker, neuron-specific enolase (NSE), and late, ciliary neurotrophic factor (CNTF), was determined with enzyme-linked immunosorbent assays (ELISAs). The genetic expression was also explored through real-time PCR. Results indicated differentiation in all experimental groups; however, cells that were preinduced showed higher proliferation and a higher differentiation rate than the group that was not preinduced. Within the preinduced groups, results indicated that cells treated with IT2 and consecutive PBM upregulated differentiation the most morphologically and physiologically.

Single and consecutive application of near-infrared and green irradiation modulates adipose derived stem cell proliferation and affect differentiation factors

Regenerative medicine uses undifferentiated adipose-derived mesenchymal stem cells (ADMSCs) to differentiate into multiple cell types. Photobiomodulation (PBM) is a rapidly growing treatment for pain and inflammation reduction, as well as tissue healing. PBM's efficacy is dependent on wavelength and energy dosage. Red (600-700 nm) and near-infrared (780-1100 nm) wavelengths have been shown to promote cell proliferation. Light wavelengths such as green (495 nm-570 nm) have been found to influence ADMSC differentiation. The initiation of ADMSC proliferation and differentiation requires physiologically relevant levels of reactive oxygen species (ROS), while increased levels inhibit self-renewal. Stem cell differentiation is guided by mitochondrial metabolism, where an increased mitochondrial membrane potential (MMP) is associated with higher in vitro differentiation capacity. ADMSCs must home to and accumulate at the sites of injury in regenerative medicine, so cell homing is critical. The aim of this in vitro study was to compare consecutive NIR (825 nm) and green (525 nm) applications on ADMSC morphology and physiology with the possibility that multiple wavelengths could lead to a combination of the two effects. The results showed that concurrent use of NIR-green irradiation significantly stimulated ADMSC proliferation, increasing population density and cellular ATP. Furthermore, NIR-green showed a time dependent increase in ROS production and was significantly higher at 7 days. Consecutive NIR-green irradiation significantly increased MMP and was most effective at facilitating ADMSC migration over time. Findings suggest that with consecutive NIR and green irradiation, the ADMSCs can rapidly proliferate, but can also be modulated for regenerative purposes.

The Effect of Photobiomodulation on Human Mesenchymal Cells: A Literature Review

BACKGROUND

Mesenchymal stem cell-based therapy is known to have the potential to induce angiogenesis. However, there are still some limitations regarding their clinical application. Photomodulation/photobiomodulation is non-invasive and non-toxic phototherapy able to stimulate cell viability, proliferation, differentiation, and migration, when the right irradiation parameters are applied. A review of the published articles on human conditioned-by-photobiomodulation mesenchymal cells in an in vitro set up was carried out. Our aim was to describe the studies' results and identify any possible tendency that might highlight the most suitable procedures.

METHODS

A search in English of the PubMed database was carried out with the search criteria: photobiomodulation or photoactivation or photomodulation, and mesenchymal cells. All irradiations applied in vitro, on human mesenchymal cells, with wavelengths ranged from 600 to 1000 nm.

RESULTS

The search yielded 42 original articles and five reviews. Finally, 37 articles were selected with a total of 43 procedures. Three procedures (7.0%) from 620 to 625 nm; 26 procedures (60.5%) from 625 to 740 nm; 13 procedures (30.2%) from 740 to 1000 nm; and one procedure (2.3%) with combinations of wavelengths. Of the 43 procedures, 14 assessed cell viability (n = 14/43, 32.6%); 34 cell proliferation (n = 34/43, 79.1%); 19 cell differentiation (n = 19/43, 44.2%); and three cell migration (n = 3/43, 7.0%).

CONCLUSIONS

Photobiomodulation is a promising technology that can impact on cell viability, differentiation, proliferation, or migration, leading to enhance its regenerative capacity.

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The Signalling Effects of Photobiomodulation on Osteoblast Proliferation, Maturation and Differentiation: A Review

Proliferation of osteoblasts is essential for maturation and mineralization of bone matrix. Ossification, the natural phase of bone-forming and hardening is a carefully regulated phase where deregulation of this process may result in insufficient or excessive bone mineralization or ectopic calcification. Osteoblasts can also be differentiated into osteocytes, populating short interconnecting passages within the bone matrix. Over the past few decades, we have seen a significant improvement in awareness and techniques using photobiomodulation (PBM) to stimulate cell function. One of the applications of PBM is the promotion of osteoblast proliferation and maturation. PBM research results on osteoblasts showed increased mitochondrial ATP production, increased osteoblast activity and proliferation, increased and pro-osteoblast expression in the presence of red and NIR radiation. Osteocyte differentiation was also accomplished using blue and green light, showing that different light parameters have various signalling effects. The current review addresses osteoblast function and control, a new understanding of PBM on osteoblasts and its therapeutic impact using various parameters to optimize osteoblast function that may be clinically important. Graphical Abstract.