Prevention of skin flap necrosis by use of adipose-derived stromal cells with light-emitting diode phototherapy

The stereological, immunohistological, and gene expression studies in an infected ischemic wound in diabetic rats treated by human adipose-derived stem cells and photobiomodulation

We investigated the impacts of photobiomodulation (PBM) and human allogeneic adipose-derived stem cells (ha-ADS) together and or alone applications on the stereological parameters, immunohistochemical characterizing of M1 and M2 macrophages, and mRNA levels of hypoxia-inducible factor (HIF-1α), basic fibroblast growth factor (bFGF), vascular endothelial growth factor-A (VEGF-A) and stromal cell-derived factor-1α (SDF-1α) on inflammation (day 4) and proliferation phases (day 8) of repairing tissues in an infected delayed healing and ischemic wound model (IDHIWM) in type 1 diabetic (DM1) rats. DM1 was created in 48 rats and an IDHIWM was made in all of them, and they were distributed into 4 groups. Group1 = control rats with no treatment. Group2 = rats received (10 × 100000 ha-ADS). Group3 = rats exposed to PBM (890 nm, 80 Hz, 3.46 J/cm2). Group4 = rats received both PBM and ha-ADS. On day 8, there were significantly higher neutrophils in the control group than in other groups (p < 0.01). There were substantially higher macrophages in the PBM + ha-ADS group than in other groups on days 4 and 8 (p < 0.001). Granulation tissue volume, on both days 4 and 8, was meaningfully greater in all treatment groups than in the control group (all, p = 0.000). Results of M1 and M2 macrophage counts of repairing tissue in the entire treatment groups were considered preferable to those in the control group (p < 0.05). Regarding stereological and macrophage phenotyping, the results of the PBM + ha-ADS group were better than the ha-ADS and PBM groups. Results of the tested gene expression of repairing tissue on inflammation and proliferation steps in PBM and PBM + ha-ADS groups were meaningfully better than the control and ha-ADS groups (p < 0.05). We showed that PBM, ha-ADS, and PBM plus ha-ADS, hastened the proliferation step of healing in an IDHIWM in rats with DM1 by regulation of the inflammatory reaction, macrophage phenotyping, and augmented granulation tissue formation. In addition PBM and PBM plus ha-ADS protocols hastened and increased mRNA levels of HIF-1α, bFGF, SDF-1α, and VEGF-A. Totally, in terms of stereological and immuno-histological tests, and also gene expression HIF-1α and VEGF-A, the results of PBM + ha-ADS were superior (additive) to PBM, and ha-ADS alone treatments.

Photobiomodulation Therapy Improves Inflammatory Responses by Modifying Stereological Parameters, microRNA-21 and FGF2 Expression

Introduction: Photobiomodulation treatment (PBMT) is a relatively invasive method for treating wounds. An appropriate type of PBMT can produce desired and directed cellular and molecular processes. The aim of this study was to investigate the impacts of PBMT on stereological factors, bacterial count, and the expression of microRNA-21 and FGF2 in an infected, ischemic, and delayed wound healing model in rats with type one diabetes mellitus. Methods: A delayed, ischemic, and infected wound was produced on the back skin of all 24 DM1 rats. Then, they were put into 4 groups at random (n=6 per group): 1=Control group day4 (CGday4); 2=Control group day 8 (CGday8); 3=PBMT group day4 (PGday4), in which the rats were exposed to PBMT and killed on day 4; 4=PBMT group day8 (PGday8), in which the rats received PBMT and they were killed on day 8. The size of the wound, the number of microbial colonies, stereological parameters, and the expression of microRNA-21 and FGF2 were all assessed in this study throughout the inflammation (day 4) and proliferation (day 8) stages of wound healing. Results: On days 4 and 8, we discovered that the PGday4 and PGday8 groups significantly improved stereological parameters in comparison with the same CG groups. In terms of ulcer area size and microbiological counts, the PGday4 and PGday8 groups performed much better than the same CG groups. Simultaneously, the biomechanical findings in the PGday4 and PGday8 groups were much more extensive than those in the same CG groups. On days 4 and 8, the expression of FGF2 and microRNA-21 was more in all PG groups than in the CG groups (P<0.01). Conclusion: PBMT significantly speeds up the repair of ischemic and MARS-infected wounds in DM1 rats by lowering microbial counts and modifying stereological parameters, microRNA-21, and FGF2 expression.

Could Light-Based Technologies Improve Stem Cell Therapy for Skin Wounds? A Systematic Review and Meta-Analysis of Preclinical Studies

Several diseases or conditions cause dermatological disorders that hinder the process of skin repair. The search for novel technologies has inspired the combination of stem cell (SC) and light-based therapies to ameliorate skin wound repair. Herein, we systematically revised the impact of photobiomodulation therapy (PBM) combined with SCs in animal models of skin wounds and quantitatively evaluated this effect through a meta-analysis. For inclusion, SCs should be irradiated in vitro or in vivo, before or after being implanted in animals, respectively. The search resulted in nine eligible articles, which were assessed for risk of bias. For the meta-analysis, studies were included only when PBM was applied in vivo, five regarding wound closure, and three to wound strength. Overall, a positive influence of SC+PBM on wound closure (MD: 9.69; 95%CI: 5.78 to 13.61, p<0.00001) and strength (SMD: 1.7, 95%CI: 0.68 to 2.72, p=0.001) was detected, although studies have shown moderate to high heterogeneity and a lack of information regarding some bias domains. Altogether, PBM seems to be an enabling technology able to be applied post-implantation of SCs for cutaneous regeneration. Our findings may guide future laboratory and clinical studies in hopes of offering wound care patients a better quality of life.

Exenatide improves random-pattern skin flap survival via TFE3 mediated autophagy augment

Random-pattern skin flaps are widely applied to rebuild and restore soft-tissue damage in reconstructive surgery; however, ischemia and subsequent ischemia-reperfusion injury lead to flap necrosis and are major complications. Exenatide, a glucagon-like peptide-1 analog, exerts therapeutic benefits for diabetic wounds, cardiac injury, and nonalcoholic fatty liver disease. Furthermore, Exenatide is a known activator of autophagy, which is a complex process of subcellular degradation that may enhance the viability of random skin flaps. In this study, we explored whether exenatide can improve skin flap survival. Our results showed that exenatide augments autophagy, increases flap viability, enhances angiogenesis, reduces oxidative stress, and alleviates pyroptosis. Coadministration of exenatide with 3-methyladenine and chloroquine, potent inhibitors of autophagy, reversed the beneficial effects, suggesting that the therapeutic benefits of exenatide for skin flaps are due largely to autophagy activation. Mechanistically, we identified that exenatide enhanced activation and nuclear translocation of TFE3, which leads to autophagy activation. Furthermore, we found that exenatide activates the AMPK-SKP2-CARM1 and AMPK-mTOR signaling pathways, which likely lead to exenatide's effects on activating TFE3. Overall, our findings suggest that exenatide may be a potent therapy to prevent flap necrosis, and we also reveal novel mechanistic insight into exenatide's effect on flap survival.

Apigenin enhances viability of random skin flaps by activating autophagy

Random skin flap is widely used in plastic surgery. However, flap necrosis caused by ischemia-reperfusion injury limits its clinical applications. Apigenin, a naturally occurring flavonoid mainly derived from plants, facilitates flap survival. In this study, we explored the effects of apigenin on flap survival and the underlying mechanisms. A total of 54 mice having a dorsal random flap model were randomly divided into control, apigenin, and apigenin +3-methyladenine groups. These groups were treated with dimethyl sulfoxide solution, apigenin, and apigenin +3-methyladenine, respectively. The animals were then euthanized to assess angiogenesis, apoptosis, oxidative stress, and autophagy levels through histological and protein analyses. Apigenin promotes survival of the skin flap area and reduces tissue edema. In addition, apigenin enhanced angiogenesis, attenuated apoptosis, alleviated oxidative stress, and activated autophagy. Interestingly, 3-methyladenine reversed the effects of apigenin on flap survival, angiogenesis, apoptosis, and oxidative stress through inhibition of autophagy. The findings of this study show that apigenin promotes angiogenesis, inhibits cell apoptosis, and lowers oxidative stress by mediating autophagy, thus the improving survival rate of random skin flaps.

Transplantation of Adipose-Derived Stem Cells Before Flap Expansion and After Expanded Flap Elevation Result in Different Effects

BACKGROUND

Studies of using mesenchymal stem cells to assist skin and soft tissue expansion have shown that stem cells can improve expansion efficiency through promoting tissue regeneration. However, the issue that whether the flap viability is also improved is unknown.

METHODS

Sixteen pigs were equally divided into 2 groups. A pair of 150 mL expanders was symmetrically inserted into each pig's dorsum. Group 1 received adipose-derived stem cells (ADSCs) injection before expansion, and group 2 received ADSCs grafting after flap elevation. After 4 weeks' expansion, a random flap measuring 2 cm × 16 cm was elevated along the long axis of each expanded flap on the pigs' back. Flap viability was measured at postoperative day 7. Histological analysis and cell tracking were performed. The expression of vascular endothelial growth factor was determined.

RESULTS

The flap viability of the ADSCs-grafted expanded flap (75.5 ± 6.6%) was similar to the control (69.4 ± 8.4%) in group 1 (transplantation before expansion). However, in group 2 (transplantation after flap elevation), the ADSCs-grafted expanded flap had a higher flap viability (92.6 ± 5.7%) compared with control (66.2 ± 7.4%). Moreover, the ADSCs-grafted expanded flap in group 1 showed increased skin thickness, collagen content, cells proliferation, vascularization, and vascular endothelial growth factor expression. Cell tracking showed that the positively stained cell differentiating into an endotheliocyte could be seen in group 2.

CONCLUSIONS

Transplantation of ADSCs before tissue expansion does not improve flap viability but can promote tissue regeneration. Injection of ADSCs after flap elevation can increase the surviving rate of the expanded flap.

Combined therapy of photobiomodulation and adipose-derived stem cells synergistically improve healing in an ischemic, infected and delayed healing wound model in rats with type 1 diabetes mellitus

OBJECTIVE

We assessed the therapeutic effects of photobiomodulation (PBM) and adipose-derived stem cell (ADS) treatments individually and together on the maturation step of repairing of a delayed healing wound model in rats with type 1 diabetes mellitus (DM1).

RESEARCH DESIGN AND METHODS

We randomly assigned 24 rats with DM1 to four groups (n=6 per group). Group 1 was the control (placebo) group. In group 2, allograft human ADSs were transplanted. Group 3 was subjected to PBM (wavelength: 890 nm, peak power output: 80 W, pulse frequency: 80 Hz, pulsed duration: 180 ns, duration of exposure for each point: 200 s, power density: 0.001 W/cm², energy density: 0.2 J/cm²) immediately after surgery, which continued for 6 days per week for 16 days. Group 4 received both the human ADS and PBM. In addition, we inflicted an ischemic, delayed healing, and infected wound simulation in all of the rats. The wounds were infected with methicillin-resistant Staphylococcus aureus (MRSA).

RESULTS

All three treatment regimens significantly decreased the amount of microbial flora, significantly increased wound strength and significantly modulated inflammatory response and significantly increased angiogenesis on day 16. Microbiological analysis showed that PBM+ADS was significantly better than PBM and ADS alone. In terms of wound closure rate and angiogenesis, PBM+ADS was significantly better than the PBM, ADS and control groups.

CONCLUSIONS

Combination therapy of PBM+ADS is more effective that either PBM or ADS in stimulating skin injury repair, and modulating inflammatory response in an MRSA-infected wound model of rats with DM1.

Photobiomodulation plus Adipose-derived Stem Cells Improve Healing of Ischemic Infected Wounds in Type 2 Diabetic Rats

In this study, we sought to investigate the impact of photobiomodulation and adipose-derived stem cells (ADS), alone and in combination, on the maturation step of wound healing in an ischemic infected delayed healing wound model in rats with type 2 diabetes mellitus (DM2). We randomly divided 24 adult male rats into 4 groups (n = 6 per group). DM2 plus an ischemic delayed healing wound were induced in all rats. The wounds were infected with methicillin-resistant Staphylococcus aureus. Group 1 was the control (placebo) group. Group 2 received only photobiomodulation (890 nm, 80 Hz, 0.324 J/cm², and 0.001 W/cm²). Group 3 received only the allograft ADS. Group 4 received allograft ADS followed by photobiomodulation. On days 0, 4, 8, 12, and 16, we performed microbiological examination (colony forming units, [CFU]), wound area measurement, wound closure rate, wound strength, and histological and stereological examinations. The results indicated that at day 16, there was significantly decreased CFU (Analysis of variance, p = 0.001) in the photobiomodulation + ADS (0.0 ± 0.0), ADS (1350 ± 212), and photobiomodulation (0.0 ± 0.0) groups compared with the control group (27250 ± 1284). There was significantly decreased wound area (Analysis of variance, p = 0.000) in the photobiomodulation + ADS (7.4 ± 1.4 mm²), ADS (11 ± 2.2 mm²), and photobiomodulation (11.4 ± 1.4 mm²) groups compared with the control group (25.2 ± 1.7). There was a significantly increased tensiometeric property (stress maximal load, Analysis of variance, p = 0.000) in the photobiomodulation + ADS (0.99 ± 0.06 N/cm²), ADS (0.51 ± 0.12 N/cm²), and photobiomodulation (0.35 ± 0.15 N/cm²) groups compared with the control group (0.18 ± 0.04). There was a significantly modulated inflammatory response in (Analysis of variance, p = 0.049) in the photobiomodulation + ADS (337 ± 96), ADS (1175 ± 640), and photobiomodulation (69 ± 54) treatments compared to control group (7321 ± 4099). Photobiomodulation + ADS gave significantly better improvements in CFU, wound area, and wound strength compared to photobiomodulation or ADS alone. Photobiomodulation, ADS, and their combination significantly hastened healing in ischemic methicillin-resistant Staphylococcus aureus infected delayed healing wounds in rats with DM2. Combined application of photobiomodulation plus ADS demonstrated an additive effect.

Oxidative Stress Alters Angiogenic and Antimicrobial Content of Extracellular Vesicles and Improves Flap Survival

Extracellular vesicles (EVs) secreted from adipose-derived mesenchymal stem cells (ADSCs) (ADSC-EVs) improve flap survival after ischemia-reperfusion injury. Exposure of parent ADSCs to oxidative stress has been shown to enhance this effect, but mechanisms are unclear. We aimed to determine whether angiogenesis-promoting protein and microRNA (miRNA) content is altered in EVs after preconditioning with hydrogen peroxide (H₂O₂ ADSC-EVs) and whether H₂O₂ ADSC-EVs can increase viability of random pattern skin flaps.

Methods

EVs secreted by human ADSCs were isolated after culture in EV-depleted medium ± H₂O₂. Nanoparticle tracking analysis determined size and concentration of purified EVs. Mass spectrometry and small RNA next-generation sequencing were performed to compare proteomic and miRNA profiles. ADSC-EVs, H₂O₂ ADSC-EVs, or vehicle were injected into random pattern skin flaps of BALB/c mice (4-5 mice per group). Viable and necrotic areas were measured on day 7, and tissues underwent histologic analysis.

Results

Angiogenic and antimicrobial protein content of EVs was altered with H₂O₂ preconditioning. Functional enrichment analysis identified constitutive photomorphogenesis 9 signalosome (known to direct vascular endothelial growth factor production) as the major enriched Gene Ontology term unique to H₂O₂ ADSC-EVs. Two miRNAs were increased, and 12 (including 10 antiangiogenic miRNAs) were reduced in H₂O₂ ADSC-EVs. Enhanced viability (P < 0.05) of flaps treated with H₂O₂ ADSC-EVs compared with vehicle corresponded to increased capillary density in the H₂O₂ group (P < 0.001).

Conclusion

Altered protein and miRNA content in ADSC-EVs after H₂O₂ pretreatment likely contributes to enhanced therapeutic effects on flap survival observed in preclinical models.

Betulinic Acid Enhances the Viability of Random-Pattern Skin Flaps by Activating Autophagy

Random-pattern skin flap replantation is commonly used to repair skin defects during plastic and reconstructive surgery. However, flap necrosis due to ischemia and ischemia-reperfusion injury limits clinical applications. Betulinic acid, a plant-derived pentacyclic triterpene, may facilitate flap survival. In the present study, the effects of betulinic acid on flap survival and the underlying mechanisms were assessed. Fifty-four mice with a dorsal random flap model were randomly divided into the control, betulinic acid group, and the betulinic acid + 3-methyladenine group. These groups were treated with dimethyl sulfoxide, betulinic acid, and betulinic acid plus 3-methyladenine, respectively. Flap tissues were acquired on postoperative day 7 to assess angiogenesis, apoptosis, oxidative stress, and autophagy. Betulinic acid promoted survival of the skin flap area, reduced tissue edema, and enhanced the number of microvessels. It also enhanced angiogenesis, attenuated apoptosis, alleviated oxidative stress, and activated autophagy. However, its effects on flap viability and angiogenesis, apoptosis, and oxidative stress were reversed by the autophagy inhibitor 3-methyladenine. Our findings reveal that betulinic acid improves survival of random-pattern skin flaps by promoting angiogenesis, dampening apoptosis, and alleviating oxidative stress, which mediates activation of autophagy.

Assisting Rapid Soft-Tissue Expansion with Adipose-Derived Stem Cells: An Experimental Study in a Pig Model

BACKGROUND

Rapid tissue expansion has been attempted, aiming at shortening the period of conventional expansion. However, it has scarcely been clinically applied because of its drawbacks such as low expansion efficiency and tissue destruction. Adipose-derived stem cell transplantation is a promising therapeutic method in regenerative medicine. However, its effects on rapid expansion remain poorly understood.

METHODS

Twenty-four expanders were implanted in the dorsum of 12 pigs. Rapid expansion persisted for 1 week with 20 ml of saline daily. The increased area of the expanded skin was measured. Histologic and ultrastructural analysis and cell tracking were performed. The expression of vascular endothelial growth factor, fibroblast growth factor-2, and epidermal growth factor was also determined.

RESULTS

The increased area of adipose-derived stem cell-grafted expanded skin (0.91 ± 0.06 cm) was significantly more than the non-adipose-derived stem cell-treated control (0.51 ± 0.05 cm) (p < 0.01). Enhanced tissue regeneration in the adipose-derived stem cell-grafted expanded skin was evidenced by increased skin thickness, proliferating cells, extracellular matrix, and vascularization (113 ± 19/mm versus control 59 ± 14/mm) (all p < 0.05). Higher expression of vascular endothelial growth factor and epidermal growth factor was observed in the adipose-derived stem cell-transplanted expanded skin (p < 0.01 and p < 0.05, respectively), whereas the expression of fibroblast growth factor-2 was higher in the non-adipose-derived stem cell-treated control (p < 0.05). Transmission electron microscopy showed that a high density of collagen fibers could be seen in the adipose-derived stem cell-treated expanded skin. Cell tracking showed that the positively stained cells could be seen.

CONCLUSION

For rapid tissue expansion, adipose-derived stem cell transplantation may limit tissue destruction and improve the expansion efficiency by promoting tissue regeneration.

Comparison of two different laser photobiomodulation protocols on the viability of random skin flap in rats

To identify the best low level laser photobiomodulation application site at the same irradiation time to increase the viability of the skin flap in rats. Eighteen male rats (Rattus norvegicus: var. Albinus, Rodentia Mammalia) were randomly distributed into three groups (n = 6). Group I (GI) was submitted to simulated laser photobiomodulation; group II (GII) was submitted to laser photobiomodulation at three points in the flap cranial base, and group III (GIII) was submitted to laser photobiomodulation at 12 points distributed along the flap. All groups were irradiated with an Indium, Galium, Aluminum, and Phosphorus diode laser (InGaAlP), 660 nm, with 50 mW power, irradiated for a total time of 240 s in continuous emission mode. The treatment started immediately after performing the cranial base random skin flap (10 × 4 cm² dimension) and reapplied every 24 h, with a total of five applications. The animals were euthanized after the evaluation of the percentage of necrosis area, and the material was collected for histological analysis on the seventh postoperative day. GII animals presented a statistically significant decrease for the necrosis area when compared to the other groups, and a statistically significant increase in the quantification of collagen when compared to the control. We did not observe a statistical difference between the TGFβ and FGF expression in the different groups evaluated. The application of laser photobiomodulation at three points of the flap cranial base was more effective than at 12 points regarding the reduction of necrosis area.

Low-Level Laser Therapy (780 nm) on VEGF Modulation at Partially Injured Achilles Tendon

OBJECTIVE

The aim of this study was to analyze the modulatory effects of near infrared (780 nm) low-level laser therapy (LLLT) on the presence of the vascular endothelial growth factor (VEGF) in the partially injured Achilles tendons of rats.

BACKGROUND

LLLT stimulates the healing process for Achilles tendon injuries, although the extent of the modulatory effect of LLLT on the VEGF levels found in the injured tendons remains unclear.

METHODS

Sixty-five male Wistar rats were distributed in the following seven groups: LASER 1, 3, and 7 (10 partially injured Achilles tendons in each group, which were treated with LLLT for 1, 3, and 7 days, respectively); Sham 1, 3, and 7 (same injury, with simulated LLLT); Control group containing the five remaining animals and in which no procedures were performed. LLLT was applied once a day for 10 sec, with a mean power of 70 mW and fluency of 17.5 J/cm(2). After euthanasia, all of the Achilles tendons were surgically removed and the VEGF levels were analyzed using immunohistochemistry.

RESULTS

The VEGF levels remained close to normal (p > 0.05) when comparing the experimental groups (LASER and Sham: 1, 3, and 7) with the Control group.

CONCLUSION

LLLT did not stimulate the expression of VEGF in the treated Achilles tendons.

Role of adipose-derived stromal cells in pedicle skin flap survival in experimental animal models

The use of skin flaps in reconstructive surgery is the first-line surgical treatment for the reconstruction of skin defects and is essentially considered the starting point of plastic surgery. Despite their excellent usability, their application includes general surgical risks or possible complications, the primary and most common is necrosis of the flap. To improve flap survival, researchers have used different methods, including the use of adipose-derived stem cells, with significant positive results. In our research we will report the use of adipose-derived stem cells in pedicle skin flap survival based on current literature on various experimental models in animals.

The dark art of light measurement: accurate radiometry for low-level light therapy

Lasers and light-emitting diodes are used for a range of biomedical applications with many studies reporting their beneficial effects. However, three main concerns exist regarding much of the low-level light therapy (LLLT) or photobiomodulation literature; (1) incomplete, inaccurate and unverified irradiation parameters, (2) miscalculation of ‘dose,’ and (3) the misuse of appropriate light property terminology. The aim of this systematic review was to assess where, and to what extent, these inadequacies exist and to provide an overview of ‘best practice’ in light measurement methods and importance of correct light measurement. A review of recent relevant literature was performed in PubMed using the terms LLLT and photobiomodulation (March 2014–March 2015) to investigate the contemporary information available in LLLT and photobiomodulation literature in terms of reporting light properties and irradiation parameters. A total of 74 articles formed the basis of this systematic review. Although most articles reported beneficial effects following LLLT, the majority contained no information in terms of how light was measured (73 %) and relied on manufacturer-stated values. For all papers reviewed, missing information for specific light parameters included wavelength (3 %), light source type (8 %), power (41 %), pulse frequency (52 %), beam area (40 %), irradiance (43 %), exposure time (16 %), radiant energy (74 %) and fluence (16 %). Frequent use of incorrect terminology was also observed within the reviewed literature. A poor understanding of photophysics is evident as a significant number of papers neglected to report or misreported important radiometric data. These errors affect repeatability and reliability of studies shared between scientists, manufacturers and clinicians and could degrade efficacy of patient treatments. Researchers need a physicist or appropriately skilled engineer on the team, and manuscript reviewers should reject papers that do not report beam measurement methods and all ten key parameters: wavelength, power, irradiation time, beam area (at the skin or culture surface; this is not necessarily the same size as the aperture), radiant energy, radiant exposure, pulse parameters, number of treatments, interval between treatments and anatomical location. Inclusion of these parameters will improve the information available to compare and contrast study outcomes and improve repeatability, reliability of studies.

Photobiomodulation in promoting wound healing: a review

Despite diverse methods being applied to induce wound healing, many wounds remain recalcitrant to all treatments. Photobiomodulation involves inducing wound healing by illuminating wounds with light emitting diodes or lasers. While used on different animal models, in vitro, and clinically, wound healing is induced by many different wavelengths and powers with no optimal set of parameters yet being identified. While data suggest that simultaneous multiple wavelength illumination is more efficacious than single wavelengths, the optimal single and multiple wavelengths must be better defined to induce more reliable and extensive healing of different wound types. This review focuses on studies in which specific wavelengths induce wound healing and on their mechanisms of action.