Low power laser irradiation and human adipose-derived stem cell treatments promote bone regeneration in critical-sized calvarial defects in rats

Photobiostimulation conjugated with stem cells or their secretome for temporomandibular joint arthritis in a rat model

BACKGROUND

Temporomandibular joint (TMJ) arthritis is a debilitating, challenging condition and different methods have been implicated for its treatment. This study aimed to test the therapeutic potentials of low-level laser therapy (LLLT) associated with adipose derived stem cells (ADSC) or their derived secretome on a murine model induced arthritis.

METHODS

Forty eight rats were divided into four groups where group I was the sham control, the rest of animals were subjected to arthritis induction using complete Freund's adjuvant, then divided as follows: group II received phosphate buffered saline (PBS) intraarticular injection and irradiation of 0 j/cm2, group III received ADSCs derived secretome and irradiation of 38 j/cm2, and group IV received ADSCs and irradiation of 38 j/cm2 as well. One and three weeks after treatment, animals were euthanized, and paraffin blocks were processed for histological assessment by hematoxylin and eosin stain with histomorphometrical analysis. Histochemical evaluation of joint proteoglycan content was performed through toluidine blue stain, and immunohistochemical staining by the proinflammatory marker tumor necrosis factor-α (TNF-α) was performed followed by the relevant statistical tests.

RESULTS

The arthritis group showed histological signs of joint injury including cartilage atrophy, articular disc fibrosis, irregular osteochondral interface, and condylar bone resorption together with high inflammatory reaction and defective proteoglycan content. In contrast, the treated groups III and IV showed much restoration of the joint structure with normal cartilage and disc thickness. The inflammation process was significantly suppressed especially after three weeks as confirmed by the significant reduction in TNF-α positive immunostaining compared to the arthritic group, and the cartilage proteoglycan content also showed significant increase relative to the arthritic group. However, no significant difference between the results of the two treated groups was detected.

CONCLUSION

LLLT conjugated with ADSCs or ADSCs derived secretome can efficiently enhance the healing of arthritic TMJs. Stem cell secretome can be applied as a safe, potent therapy. However, further investigations are required to unravel its mechanism of action and pave its way as a safe, novel, cell free therapy.

Biomaterials combined with ADSCs for bone tissue engineering: current advances and applications

In recent decades, bone tissue engineering, which is supported by scaffold, seed cells and bioactive molecules (BMs), has provided new hope and direction for treating bone defects. In terms of seed cells, compared to bone marrow mesenchymal stem cells, which were widely utilized in previous years, adipose-derived stem cells (ADSCs) are becoming increasingly favored by researchers due to their abundant sources, easy availability and multi-differentiation potentials. However, there is no systematic theoretical basis for selecting appropriate biomaterials loaded with ADSCs. In this review, the regulatory effects of various biomaterials on the behavior of ADSCs are summarized from four perspectives, including biocompatibility, inflammation regulation, angiogenesis and osteogenesis, to illustrate the potential of combining various materials with ADSCs for the treatment of bone defects. In addition, we conclude the influence of additional application of various BMs on the bone repair effect of ADSCs, in order to provide more evidences and support for the selection or preparation of suitable biomaterials and BMs to work with ADSCs. More importantly, the associated clinical case reports and experiments are generalized to provide additional ideas for the clinical transformation and application of bone tissue engineering loaded with ADSCs.

Backscatter from therapeutic doses of ionizing irradiation does not impair cell migration on titanium implants in vitro

OBJECTIVE

The influence of radiation backscatter from titanium on DNA damage and migration capacity of human osteoblasts (OBs) and mesenchymal stem cells (MSCs) may be critical for the osseointegration of dental implants placed prior to radiotherapy. In order to evaluate effects of radiation backscatter, the immediate DNA damage and migration capacity of OBs and MSCs cultured on titanium or plastic were compared after exposure to ionizing irradiation.

MATERIALS AND METHODS

Human OBs and MSCs were seeded on machined titanium, moderately rough fluoride-modified titanium, or tissue culture polystyrene, and irradiated with nominal doses of 2, 6, 10, or 14 Gy. Comet assay was performed immediately after irradiation, while a scratch wound healing assay was initiated 24 h post-irradiation. Fluorescent live cell imaging documented the migration.

RESULTS

DNA damage increased with higher dose and with backscatter from titanium, and MSCs were significantly more affected than OBs. All doses of radiation accelerated the cell migration on plastic, while only the highest dose of 10 Gy inhibited the migration of both cell types on titanium.

CONCLUSIONS

High doses (10 Gy) of radiation inhibited the migration capacity of both cell types on titanium, whereas lower doses (2 and 6 Gy) did not affect the migration of either OBs or MSCs.

CLINICAL RELEVANCE

Fractionated doses of 2 Gy/day, as distributed in conventional radiotherapy, appear not to cause severe DNA damage or disturb the migration of OBs or MSCs during osseointegration of dental implants.

Nd:YAG-photobiomodulation enhanced ADSCs multilineage differentiation and immunomodulation potentials

To investigate the effects of Nd: YAG (1064 nm) photobiomodulation on multilineage differentiation and immunomodulation potentials of adipose tissue-derived stem cells (ADSCs) in vitro and in vivo. For in vitro experiments, cells were divided into the control group (non-irradiated control ADSCs) and photobiomodulation groups. 0.5 J/cm2, 1 J/cm2, 2 J/cm2, and 4 J/cm2 were used for proliferation assays; for ADSCs adipogenic differentiation assays, 0.5 J/cm2, 1 J/cm2 were applied; 1 J/cm2 was used for migration and immunomodulation assays. The differentiation abilities were assessed by qPCR, Oil Red O staining, and Alizarin Red staining. The immunomodulation potential was assessed by qPCR and human cytokine array. DSS-induced colitis model. was used to test the effect of photobiomodulation on ADSCs immunomodulation potentials in vivo. Nd:YAG-based photobiomodulation dose-dependently promoted ADSCs proliferation and migration; 1 J/cm2 showed the best promotion effect on proliferation. Moreover, Nd:YAG photobiomodulation promoted ADSCs osteogenic differentiation and brown adipose adipogenic differentiation. The potential immunomodulation assays showed Nd:YAG photobiomodulation improved Anti-inflammation capacity of ADSCs and photobiomodulation irradiated ADSCs effectively alleviated DSS-induced colitis severity in vivo. Our study suggests Nd:YAG photobiomodulation might enhance the ADSCs multilineage differentiation and immunomodulation potentials. These results might help to enhance ADSCs therapeutic effects for clinical application. However, further studies are needed to explore the mechanisms of Nd:YAG photobiomodulation promoting multilineage differentiation and immunomodulation potentials of ADSCs.

Regenerative Medicine and Rehabilitation Therapy in the Canine

Regenerative medicine is used in the canine to optimize tissue healing and treat osteoarthritis and soft tissue injuries. Rehabilitation therapy is also often implemented in the treatment and management of musculoskeletal conditions in the canine. Initial experimental studies have shown that regenerative medicine and rehabilitation therapy may work safely and synergistically to enhance tissue healing. Although additional study is required to define optional rehabilitation therapy protocols after regenerative medicine therapy in the canine, certain fundamental principles of rehabilitation therapy still apply to patients treated with regenerative medicine.

MSC-Exos: Important active factor of bone regeneration

Bone defect and repair is a common but difficult problem in restorative and reconstructive surgery. Bone tissue defects of different sizes caused by different reasons bring functional limitations and cosmetic deformities to patients. Mesenchymal stem cells (MSC), a major hotspot in the field of regeneration in recent years, have been widely used in various studies on bone tissue regeneration. Numerous studies have shown that the bone regenerative effects of MSC can be achieved through exosome-delivered messages. Although its osteogenic mechanism is still unclear, it is clear that MSC-Exos can directly or indirectly support the action of bone regeneration. It can act directly on various cells associated with osteogenesis, or by carrying substances that affect cellular activators or the local internal environment in target cells, or it can achieve activation of the osteogenic framework by binding to materials. Therefore, this review aims to summarize the types and content of effective contents of MSC-Exos in bone regeneration, as well as recent advances in the currently commonly used methods to enable the binding of MSC-Exos to the framework and to conclude that MSC-Exos is effective in promoting osteogenesis.

Current applications of adipose-derived mesenchymal stem cells in bone repair and regeneration: A review of cell experiments, animal models, and clinical trials

In the field of orthopaedics, bone defects caused by severe trauma, infection, tumor resection, and skeletal abnormalities are very common. However, due to the lengthy and painful process of related surgery, people intend to shorten the recovery period and reduce the risk of rejection; as a result, more attention is being paid to bone regeneration with mesenchymal stromal cells, one of which is the adipose-derived mesenchymal stem cells (ASCs) from adipose tissue. After continuous subculture and cryopreservation, ASCs still have the potential for multidirectional differentiation. They can be implanted in the human body to promote bone repair after induction in vitro, solve the problems of scarce sources and large damage, and are expected to be used in the treatment of bone defects and non-union fractures. However, the diversity of its differentiation lineage and the lack of bone formation potential limit its current applications in bone disease. Here, we concluded the current applications of ASCs in bone repair, especially with the combination and use of physical and biological methods. ASCs alone have been proved to contribute to the repair of bone damage in vivo and in vitro. Attaching to bone scaffolds or adding bioactive molecules can enhance the formation of the bone matrix. Moreover, we further evaluated the efficiency of ASC-committed differentiation in the bone in conditions of cell experiments, animal models, and clinical trials. The results show that ASCs in combination with synthetic bone grafts and biomaterials may affect the regeneration, augmentation, and vascularization of bone defects on bone healing. The specific conclusion of different materials applied with ASCs may vary. It has been confirmed to benefit osteogenesis by regulating osteogenic signaling pathways and gene transduction. Exosomes secreted by ASCs also play an important role in osteogenesis. This review will illustrate the understanding of scientists and clinicians of the enormous promise of ASCs’ current applications and future development in bone repair and regeneration, and provide an incentive for superior employment of such strategies.

Photobiomodulation in 3D tissue engineering

SIGNIFICANCE

The method of photobiomodulation (PBM) has been used in medicine for a long time to promote anti-inflammation and pain-resolving processes in different organs and tissues. PBM triggers numerous cellular pathways including stimulation of the mitochondrial respiratory chain, alteration of the cytoskeleton, cell death prevention, increasing proliferative activity, and directing cell differentiation. The most effective wavelengths for PBM are found within the optical window (750 to 1100 nm), in which light can permeate tissues and other water-containing structures to depths of up to a few cm. PBM already finds its applications in the developing fields of tissue engineering and regenerative medicine. However, the diversity of three-dimensional (3D) systems, irradiation sources, and protocols intricate the PBM applications.

AIM

We aim to discuss the PBM and 3D tissue engineered constructs to define the fields of interest for PBM applications in tissue engineering.

APPROACH

First, we provide a brief overview of PBM and the timeline of its development. Then, we discuss the optical properties of 3D cultivation systems and important points of light dosimetry. Finally, we analyze the cellular pathways induced by PBM and outcomes observed in various 3D tissue-engineered constructs: hydrogels, scaffolds, spheroids, cell sheets, bioprinted structures, and organoids.

RESULTS

Our summarized results demonstrate the great potential of PBM in the stimulation of the cell survival and viability in 3D conditions. The strategies to achieve different cell physiology states with particular PBM parameters are outlined.

CONCLUSIONS

PBM has already proved itself as a convenient and effective tool to prevent drastic cellular events in the stress conditions. Because of the poor viability of cells in scaffolds and the convenience of PBM devices, 3D tissue engineering is a perspective field for PBM applications.

A Comparative Analysis of Photobiomodulation-Mediated Biological Effects of Single Versus Double Irradiation on Dental Pulp Stem Cells: An In Vitro Study

Objective: In recent years, fractionated irradiation protocols, rather than a simple plan of exposure, have been proposed as a more effective method in the field of tissue regeneration. Thus, this study aimed at a comparative analysis of single versus double irradiation of an 808-nm diode laser, in terms of dental pulp stem cells' (DPSCs) viability and proliferation in vitro. Methods: Subcultured DPSCs were either irradiated, or not (control group), with energy densities of 3, 7, and 12 J·cm^-2 in a single- or double-session manner (24 h apart). On 0, 12, 24, 48, and 72 h postirradiation, cell viability and proliferation were evaluated through Trypan Blue and alamarBlue assays, respectively. Results: During the first 48 h postirradiation, the highest rates of DPSC proliferation were assigned to double irradiation at 3 or single exposure to 7 J⋅cm^-2, with no cytotoxic effects on cell viability. Inversely, single irradiation at 12, or a double session of exposure to 7 or 12 J⋅cm^-2, led to a significant descent in the rates of proliferation and cell viability. Conclusions: Within the limitations of this study, evidence suggests a positive impact on the biological responses of DPSCs following double session of exposure to lower energy densities as well as a single irradiation at a higher energy dosage.

Different Protocols of Combined Application of Photobiomodulation In Vitro and In Vivo Plus Adipose-Derived Stem Cells Improve the Healing of Bones in Critical Size Defects in Rat Models

Introduction: Long bone segmental deficiencies are challenging complications to treat. Hereby, the effects of the scaffold derived from the human demineralized bone matrix (hDBMS) plus human adipose stem cells (hADSs) plus photobiomodulation (PBM) (in vitro and or in vivo) on the catabolic step of femoral bone repair in rats with critical size femoral defects (CDFDs) were evaluated with stereology and high stress load (HSL) assessment methods. Methods: hADSs were exposed to PBM in vitro; then, the mixed influences of hDBMS+hADS+PBM on CSFDs were evaluated. CSFDs were made on both femurs; then hDBMSs were engrafted into both CSFDs of all rats. There were 6 groups (G)s: G1 was the control; in G2 (hADS), hADSs only were engrafted into hDBMS of CSFD; in G3 (PBM) only PBM therapy for CSFD was provided; in G4 (hADS+PBM in vivo), seeded hADSs on hDBMS of CSFDs were radiated with a laser in vivo; in G5 (hADSs+PBM under in vitro condition), hADSs in a culture system were radiated with a laser, then transferred on hDBMS of CSFDs; and in G6 (hADS+PBM in conditions of in vivo and in vitro), laser-exposed hADSs were transplanted on hDBMS of CSFDs, and then CSFDs were exposed to a laser in vivo. Results: Groups 4, 5, and 6 meaningfully improved HSLs of CSFD in comparison with groups 3, 1, and 2 (all, P=0.001). HSL of G5 was significantly more than G4 and G6 (both, P=0.000). Gs 6 and 4 significantly increased new bone volumes of CSFD compared to Gs 2 (all, P=0.000) and 1 (P=0.001 & P=0.003 respectively). HSL of G 1 was significantly lower than G5 (P=0.026). Conclusion: HSLs of CSFD in rats that received treatments of hDBMS plus hADS plus PBM were significantly higher than treatments with hADS and PBM alone and control groups.

Optimal Parameters of Laser Therapy to Improve Critical Calvarial Defects

Body bones play diverse pivotal roles, including the protection of vital organs. For instance, the integrative functions of the brain controlling diverse peripheral actions can be affected by a traumatic injury on the calvaria and the reparative process of a large defect is a challenge in the integrative physiology. Therefore, the development of biomaterials and approaches to improve such defects still requires substantial advances. In this regard, the most attractive approaches have been covering the cavity with inorganic bovine bone (IBB) and, more recently, also using low-level laser therapy (LT), but this issue has opened many questions. Here, it was determined the number of LT sessions required to speed up and to intensify the recovery process of two 5-mm-diameter defects promoted in the calvaria of each subgroup of six adult Wistar rats. The quantitative data showed that 30 days post-surgery, the recovery process by using blood clot-filling was not significantly influenced by the number of LT sessions. However, in the IBB-filled defects, the number of LT sessions markedly contributed to the improvement of the reparative process. Compared to the Control group (non-irradiated), the percentage of mineralization (formation of new bone into the cavities) gradually increased 25, 49, and 52% with, respectively, 4, 7, and 11 sessions of LT. In summary, combining the use of IBB with seven sessions of LT seems to be an optimal approach to greatly improve the recovery of calvarial defects. This translational research opens new avenues targeting better conditions of life for those suffering from large bone traumas and in the present field could contribute to preserve the integrative functions of the brain.

Evaluation of the effects of preconditioned human stem cells plus a scaffold and photobiomodulation administration on stereological parameters and gene expression levels in a critical size bone defect in rats

We assessed the impact of photobiomodulation (PBM) plus adipose-derived stem cells (ASCs) during the anabolic and catabolic stages of bone healing in a rat model of a critical size femoral defect (CSFD) that was filled with a decellularized bone matrix (DBM). Stereological analysis and gene expression levels of bone morphogenetic protein 4 (BMP4), Runt-related transcription factor 2 (RUNX2), and stromal cell-derived factor 1 (SDF1) were determined. There were six groups of rats. Group 1 was the untreated control or DBM. Study groups 2-6 were treated as follows: ASC (ASC transplanted into DBM, then implanted in the CSFD); PBM (CSFD treated with PBM); irradiated ASC (iASC) (ASCs preconditioned with PBM, then transplanted into DBM, and implanted in the CSFD); ASC + PBM (ASCs transplanted into DBM, then implanted in the CSFD, followed by PBM administration); and iASC + PBM (the same as iASC, except CSFDs were exposed to PBM). At the anabolic step, all treatment groups had significantly increased trabecular bone volume (TBV) (24.22%) and osteoblasts (83.2%) compared to the control group (all, p = .000). However, TBV in group iASC + PBM groups were superior to the other groups (97.48% for osteoblast and 58.8% for trabecular bone volume) (all, p = .000). The numbers of osteocytes in ASC (78.2%) and iASC + PBM (30%) groups were remarkably higher compared to group control (both, p = .000). There were significantly higher SDF (1.5-fold), RUNX2 (1.3-fold), and BMP4 (1.9-fold) mRNA levels in the iASC + PBM group compared to the control and some of the treatment groups. At the catabolic step of bone healing, TBV increased significantly in PBM (30.77%), ASC + PBM (32.27%), and iASC + PBM (35.93%) groups compared to the control group (all, p = .000). There were significantly more osteoblasts and osteocytes in ASC (71.7%, 62.02%) (p = .002, p = .000); PBM (82.54%, 156%), iASC (179%, 23%), and ASC + PBM (108%, 110%) (all, p = .000), and iASC + PBM (79%, 100.6%) (p = .001, p = .000) groups compared to control group. ASC preconditioned with PBM in vitro plus PBM in vivo significantly increased stereological parameters and SDF1, RUNX2, and BMP4 mRNA expressions during bone healing in a CSFD model in rats.

In vivo efficacy of low-level laser therapy on bone regeneration

PURPOSE

In clinical use of low-level laser therapy for bone regeneration (LLLT), application protocol (dose, duration, and repetitions) has not been established. This study aimed to depict a reliable dosage of LLLT by evaluating the efficacy of different dosing of LLLT (diode) on the healing of rabbit cranial defects.

METHODS

Critical size defects were prepared in calvarias of 26 New Zealand White Rabbits in such each animal containing both test and control groups. Test groups were irradiated with 4 Joule/cm² (j/cm²), 6 j/cm², and 8 j/cm². The rabbits were subjected to six times of laser treatments in 10 days. At the end of the second week, 5 rabbits were sacrificed for histopathological and immunohistochemical analyses. At the 4th and 8th weeks, 20 rabbits (10 each) were sacrificed for micro-CT and histopathological analyses.

RESULTS

Micro-CT evaluation revealed improved new bone formation in all test groups compared to the control group. 6 j/cm² group demonstrated the highest bone formation. The highest bone morphogenic protein -2 levels were found in the 4 j/cm² group. Osteocalcin expression was significantly higher in 4 j/cm² group.

CONCLUSIONS

Our findings indicate that LLLT have a positive effect on new bone formation. The high efficacy of doses of 4 j/cm² and 6 j/cm² is promising to promote early bone healing.

Simultaneous Treatment of Photobiomodulation and Demineralized Bone Matrix With Adipose-Derived Stem Cells Improve Bone Healing in an osteoporotic bone defect

Introduction: The ability of simultaneous treatment of critical-sized femoral defects (CSFDs) with photobiomodulation (PBM) and demineralized bone matrix (DBM) with or without seeded adipose-derived stem cells (ASCs) to induce bone reconstruction in ovariectomized induced osteoporotic (OVX) rats was investigated. Methods: The OVX rats with CSFD were arbitrarily separated into 6 groups: control, scaffold (S, DBM), S + PBM, S + alendronate (ALN), S + ASCs, and S + PBM + ASCs. Each group was assessed by cone beam computed tomography (CBCT) and histological examinations. Results: In the fourth week, CBCT and histological analyses revealed that the largest volume of new bone formed in the S + PBM and S + PBM + ASC groups. The S + PBM treatment relative to the S and S + ALN treatments remarkably reduced the CSFD (Mann-Whitney test, P = 0.009 and P = 0.01). Furthermore, S + PBM + ASCs treatment compared to the S and S + ALN treatments significantly decreased CSFD (Mann Whitney test, P = 0.01). In the eighth week, CBCT analysis showed that extremely enhanced bone regeneration occurred in the CSFD of the S + PBM group. Moreover, the CSFD in the S + PBM group was substantially smaller than S, S + ALN and S + ASCs groups (Mann Whitney test, P = 0.01, P = 0.02 and P = 0.009). Histological observations showed more new bone formation in the treated CSFD of S + PBM + ASCs and S + PBM groups. Conclusion: The PBM plus DBM with or without ASCs significantly enhanced bone healing in the CSFD in OVX rats compared to control, DBM alone, and ALN plus DBM groups. The PBM plus DBM with or without ASCs significantly decreased the CSFD area compared to either the solo DBM or ALN plus DBM treatments.

Comparison of Osteogenic Potentials of Dental Pulp and Bone Marrow Mesenchymal Stem Cells Using the New Cell Transplantation Platform, CellSaic, in a Rat Congenital Cleft-Jaw Model

Scaffolds stimulate cell proliferation and differentiation and play major roles in providing growth and nutrition factors in the repair of bone defects. We used the recombinant peptide Cellnest™ to prepare the three-dimensional stem cell complex, CellSaic, and evaluated whether CellSaic containing rat dental pulp stem cells (rDPSCs) was better than that containing rat bone marrow stem cells (rBMSCs). rDPSC-CellSaic or rBMSC-CellSaic, cultured with or without osteogenic induction medium, formed the experimental and control groups, respectively. Osteoblast differentiation was evaluated in vitro and transplanted into a rat model with a congenital jaw fracture. Specimens were collected and evaluated by microradiology and histological analysis. In the experimental group, the amount of calcium deposits, expression levels of bone-related genes (RUNX2, ALP, BSP, and COL1), and volume of mineralized tissue, were significantly higher than those in the control group (p < 0.05). Both differentiated and undifferentiated rDPSC-CellSaic and only the differentiated rBMSC-CellSaic could induce the formation of new bone tissue. Overall, rBMSC-CellSaic and rDPSC-CellSaic made with Cellnest™ as a scaffold, provide excellent support for promoting bone regeneration in rat mandibular congenital defects. Additionally, rDPSC-CellSaic seems a better source for craniofacial bone defect repair than rBMSC-CellSaic, suggesting the possibility of using DPSCs in bone tissue regenerative therapy.

Biological Responses of Stem Cells to Photobiomodulation Therapy

BACKGROUND

Stem cells have attracted the researchers interest, due to their applications in regenerative medicine. Their self-renewal capacity for multipotent differentiation, and immunomodulatory properties make them unique to significantly contribute to tissue repair and regeneration applications. Recently, stem cells have shown increased proliferation when irradiated with low-level laser therapy or Photobiomodulation Therapy (PBMT), which induces the activation of intracellular and extracellular chromophores and the initiation of cellular signaling. The purpose of this study was to evaluate this phenomenon in the literature.

METHODS

The literature investigated the articles written in English in four electronic databases of PubMed, Scopus, Google Scholar and Cochrane up to April 2019. Stem cell was searched by combining the search keyword of "low-level laser therapy" OR "low power laser therapy" OR "low-intensity laser therapy" OR "photobiomodulation therapy" OR "photo biostimulation therapy" OR "LED". In total, 46 articles were eligible for evaluation.

RESULTS

Studies demonstrated that red to near-infrared light is absorbed by the mitochondrial respiratory chain. Mitochondria are significant sources of reactive oxygen species (ROS). Mitochondria play an important role in metabolism, energy generation, and are also involved in mediating the effects induced by PBMT. PBMT may result in the increased production of (ROS), nitric oxide (NO), adenosine triphosphate (ATP), and cyclic adenosine monophosphate (cAMP). These changes, in turn, initiate cell proliferation and induce the signal cascade effect.

CONCLUSION

The findings of this review suggest that PBMT-based regenerative medicine could be a useful tool for future advances in tissue engineering and cell therapy.

The Role of Adipose Stem Cells in Bone Regeneration and Bone Tissue Engineering

Bone regeneration is a complex process that is influenced by tissue interactions, inflammatory responses, and progenitor cells. Diseases, lifestyle, or multiple trauma can disturb fracture healing, which might result in prolonged healing duration or even failure. The current gold standard therapy in these cases are bone grafts. However, they are associated with several disadvantages, e.g., donor site morbidity and availability of appropriate material. Bone tissue engineering has been proposed as a promising alternative. The success of bone-tissue engineering depends on the administered cells, osteogenic differentiation, and secretome. Different stem cell types offer advantages and drawbacks in this field, while adipose-derived stem or stromal cells (ASCs) are in particular promising. They show high osteogenic potential, osteoinductive ability, and immunomodulation properties. Furthermore, they can be harvested through a noninvasive process in high numbers. ASCs can be induced into osteogenic lineage through bioactive molecules, i.e., growth factors and cytokines. Moreover, their secretome, in particular extracellular vesicles, has been linked to fracture healing. The aim of this review is a comprehensive overview of ASCs for bone regeneration and bone tissue engineering.

Poly(lactic-co-glycolic acid)-based composite bone-substitute materials

Research and development of the ideal artificial bone-substitute materials to replace autologous and allogeneic bones for repairing bone defects is still a challenge in clinical orthopedics. Recently, poly(lactic-co-glycolic acid) (PLGA)-based artificial bone-substitute materials are attracting increasing attention as the benefit of their suitable biocompatibility, degradability, mechanical properties, and capabilities to promote bone regeneration. In this article, we comprehensively review the artificial bone-substitute materials made from PLGA or the composites of PLGA and other organic and inorganic substances, elaborate on their applications for bone regeneration with or without bioactive factors, and prospect the challenges and opportunities in clinical bone regeneration.

Effects of photobiomodulation on bone defects grafted with bone substitutes: A systematic review of in vivo animal studies

A present, photobiomodulation therapy (PBMT) effectiveness in enhancing bone regeneration in bone defects grafted with or without biomaterials is unclear. This systematic review (PROSPERO, ref. CRD 42019148959) aimed to critically appraise animal in vivo published data and present the efficacy of PBMT and its potential synergistic effects on grafted bone defects. MEDLINE, CCCT, Scopus, Science Direct, Google Scholar, EMBASE, EBSCO were searched, utilizing the following keywords: bone repair; low-level laser therapy; LLLT; light emitting diode; LEDs; photobiomodulation therapy; in vivo animal studies, bone substitutes, to identify studies between 1994 and 2019. After applying the eligibility criteria, 38 papers included where the results reported according to "PRISMA." The results revealed insufficient and incomplete PBM parameters, however, the outcomes with or without biomaterials have positive effects on bone healing. In conclusion, in vivo animal studies with a standardized protocol to elucidate the effects of PBMT on biomaterials are required initially prior to clinical studies.

Bone marrow coagulated and low-level laser therapy accelerate bone healing by enhancing angiogenesis, cell proliferation, osteoblast differentiation, and mineralization

The present study evaluated bone marrow aspirate (BMA) and low-level laser therapy (LLLT) on bone healing. It was created critical-size defects (CSD) of 5 mm diameter in rat calvaria of 64 rats. Animals were randomly divided into four groups: Control (blood clot), BMA (coagulated BMA), LLLT (laser irradiation and blood clot), and BMA/LLLT (laser irradiation and coagulated BMA). Euthanasia was performed at 15 or 30 days postoperative. Immunohistochemical reactions were performed to identify vascular endothelial growth factor (VEGF), proliferating cell nuclear antigen (PCNA), runt-related transcription factor-2 (Runx2), bone morphogenetic protein-2 (BMP-2), osteocalcin (OCN), and osteopontin (OPN). The markers were quantified, and data were statistically analyzed. Groups BMA/LLLT and LLLT presented significantly higher VEGF expression than group control. Group BMA/LLLT presented a significantly higher expression of PCNA than all experimental groups. Groups BMA and BMA/LLLT presented significantly higher expression of BMP-2 than all experimental groups. Groups LLLT and BMA/LLLT presented significantly higher expression of OPN than groups control and BMA. Groups LLLT, BMA, and BMA/LLLT presented a significantly higher expression of OCN than group control. It can be concluded that the association of BMA and LLLT enhanced bone healing by improving expression of VEGF, PCNA, Runx2, BMP-2, OPN, and OCN.

Photobiomodulation therapy inhibits oral submucous fibrosis in mice

Objectives

Oral submucous fibrosis (OSMF) is a chronic inflammatory disease and a potentially malignant oral disorder. However, the best therapeutic treatment for OSMF remains uncertain. Our previous study showed that photobiomodulation (PBM) therapy and forskolin could reduce arecoline‐induced fibrosis reactions via the cAMP pathway. The present study aimed to establish an animal model of areca nut extract (ANE)‐induced OSMF and to evaluate the therapeutic potential of PBM and forskolin for ANE‐induced OSMF.

Subjects and methods

The mice were divided into five groups. The buccal tissues were harvested for histomorphological analysis and immunoblotting.

Results

Our results showed that PBM significantly reduced the development of ANE‐induced OSMF, quantified by changes in submucosal layer thickness and collagen deposition. Additionally, PBM could extensively reduce the protein expression of the fibrotic marker genes alpha‐smooth muscle actin (α‐SMA) and connective tissue growth factor (CTGF) in buccal submucous lesions. However, forskolin treatment significantly decreased the protein expression of fibrotic marker genes but slightly decreased the observed histomorphological changes.

Conclusions

We established an ANE‐induced OSMF mouse model, which also provided a model for the development of a therapeutic treatment for OSMF. The anti‐fibrotic effects of PBM and forskolin may be useful for clinical interventions.

Adipose-derived stem cells: An appropriate selection for osteogenic differentiation

Mesenchymal stem cells (MSCs) are a major component of various forms of tissue engineering. MSCs have self-renewal and multidifferential potential. Osteogenic differentiation of MSCs is an area of attention in bone regeneration. One form of MSCs are adipose-derived stem cells (ASCs), which can be simply harvested and differentiated into several cell lineages, such as chondrocytes, adipocytes, or osteoblasts. Due to special properties, ASCs are frequently used in vitro and in vivo bone regeneration. Identifying factors involved in osteogenic differentiation of ASCs is important for better understanding the mechanism of osteogenic differentiation. Different methods are used to stimulate osteogenesis of ASCs in literature, including common osteogenic media, growth factors, hormones, hypoxia, mechanical and chemical stimuli, genetic modification, and nanotechnology. This review article provides an overview describing the isolation procedure, characterization, properties, current methods for osteogenic differentiation of ASCs, and their basic biological mechanism.

The Future of Facial Fat Grafting

Fat grafting was first described in the early 20th century but for many years remained a relatively underused technique due to the unreliability of long-term volume expansion. Significant improvements in reliability have been made in the last 2 decades and there is a large body of literature pertaining to extraction, processing and injection methods to obtain more lasting effects. However, volume loss and graft resorption remain a major challenge in the long term and lead to unpredictability in results. Enriching adipose graft with stromal vascular fraction, ex vivo cultured adipose stem cells and platelet-derived growth factor among others is one method under active investigation which may assist graft survival through a range of mechanisms including increased angiogenesis. Breaking adipose graft into smaller fragments such that engrafted cells have greater access to donor-site oxygenation and nutrition is another method which in theory may promote survival. Presently, adipose grafting in the face is usually for the addition of volume to fill defects. However, the stem-cell containing fraction of adipose grafting (stromal vascular fraction) appears to exert a rejuvenating effect on overlying skin and soft tissue when administered alone. The application of these low-volume injections represents a significant shift in thinking away from mere volume expansion. These techniques have been tested in a range of animal models and some human studies. In this review, the authors provide a broad overview of present research and highlight both limitations in previous research and current areas of investigation.

Adipose-derived stem cell sheets accelerate bone healing in rat femoral defects

In the present study, we investigated whether both adipose-derived stem cell (ADSC) and osteogenic-induced ADSC sheets could promote bone healing in a rat distal femoral metaphysis bone defect model. A through-hole defect of 1 mm diameter was drilled into each distal femur of 12 week old rats. Forty-five rats were randomly assigned to three groups: (1) control group; (2) ADSC sheet group; or (3) osteogenic-induced ADSC sheet group. We evaluated each group by analysis of computerized tomography scans every week after the surgery, histological analysis, and DiI labeling (a method of membrane staining for post implant cell tracing). Radiological and histological evaluations showed that a part of the hole persisted in the control group at four weeks after surgery, whereas the hole was restored almost completely by new bone formation in both sheet groups. The mean value of bone density (in Houndsfield units) for the bone defect area was significantly higher in both sheet groups than that in the control group (p = 0.05) at four weeks postoperative. A large number of osteocalcin positive osteoblasts were observed at the area of bone defect, especially in the osteogenic-induced ADCS sheet group. DiI labeling in the newly formed bone showed that each sheet had differentiated into bone tissue at four weeks after surgery. The ADSC and the osteogenic-induced ADSC sheets promoted significantly quicker bone healing in the bone defect. Moreover, the osteogenic-induced ADSC sheet may be more advantageous for bone healing than the ADSC sheet because of the higher number of osteocalcin positive osteoblasts via the transplantation.

Osteogenesis of Multipotent Progenitor Cells using the Epigallocatechin Gallate-Modified Gelatin Sponge Scaffold in the Rat Congenital Cleft-Jaw Model

Cost-effective and functionalized scaffolds are in high demand for stem-cell-based regenerative medicine to treat refractory bone defects in craniofacial abnormalities and injuries. One potential strategy is to utilize pharmacological and cost-effective plant polyphenols and biocompatible proteins, such as gelatin. Nevertheless, the use of chemically modified proteins with plant polyphenols in this strategy has not been standardized. Here, we demonstrated that gelatin chemically modified with epigallocatechin gallate (EGCG), the major catechin isolated from green tea, can be a useful material to induce bone regeneration in a rat congenial cleft-jaw model in vivo when used with/without adipose-derived stem cells or dedifferentiated fat cells. Vacuum-heated gelatin sponges modified with EGCG (vhEGCG-GS) induced superior osteogenesis from these two cell types compared with vacuum-heated gelatin sponges (vhGS). The EGCG-modification converted the water wettability of vhGS to a hydrophilic property (contact angle: 110° to 3.8°) and the zeta potential to a negative surface charge; the modification enhanced the cell adhesion property and promoted calcium phosphate precipitation. These results suggest that the EGCG-modification with chemical synthesis can be a useful platform to modify the physicochemical property of gelatin. This alteration is likely to provide a preferable microenvironment for multipotent progenitor cells, inducing superior bone formation in vivo.