Influence of Different Photobiomodulation Parameters on Multi-Potent Adipose Tissue Mesenchymal Cells In Vitro

Objective: Investigating the effect of different parameters of photobiomodulation (PBM) with low-power laser on multi-potent mesenchymal stem cells (MSCs) derived from adipose tissue in terms of proliferation and cell death. Methods: MSCs were submitted to PBM applications with combinations of the following physical parameters: control group (no intervention), wavelengths of 660 and 830 nm; energy of 0.5, 2, and 4 J; and power of 40 and 100 mW. MSC analysis was performed using MetaXpress® software at 24, 48, and 72 h. Results: Irradiation promoted a significant increase in cell proliferation (p < 0.05), with 830 nm laser, 100 mW, with energy of 0.5, 2, and 4 J in relation to the control group at all times. PBM with 660 nm, power of 40 mW, and energy of 0.5, 2, and 4 J produced greater cell death at 24 h compared with the control group. At the time of 72 h, there was no significant difference concerning cell death. Conclusions: According to the results found, we can conclude that both wavelengths were effective; however, the 830 nm laser was more effective in terms of cell proliferation compared with the 660 nm laser. The 660 nm wavelength showed a significant increase in cell death when compared with the 830 nm laser.

Effect of photobiomodulation therapy on the morphology, intracellular calcium concentration, free radical generation, apoptosis and necrosis of human mesenchymal stem cells-an in vitro study

The aim of the study was to investigate the impact of multiwave locked system (MLS M1) emitting synchronized laser radiation at 2 wavelength simultaneous (λ = 808 nm, λ = 905 nm) on the mesenchymal stem cells (MSCs). Human MSCs were exposed to MLS M1 system laser radiation with the power density 195-318 mW/cm2 and doses of energy 3-20 J, in continuous wave emission (CW) or pulsed emission (PE). After irradiation exposure in doses of energy 3 J, 10 J (CW, ƒ = 1000 Hz), and 20 J (ƒ = 2000 Hz), increased proliferation of MSCs was observed. Significant reduction of Fluo-4 Direct™ Ca2+ indicator fluorescence over controls after CW and PE with 3 J, 10 J, and 20 J was noticed. A decrease in fluorescence intensity after the application of radiation with a frequency of 2000 Hz in doses of 3 J, 10 J, and 20 J was observed. In contrary, an increase in DCF fluorescence intensity after irradiation with laser radiation of 3 J, 10 J, and 20 J (CW, ƒ = 1000 Hz and ƒ = 2000 Hz) was also shown. Laser irradiation at a dose of 20 J, emitted at 1000 Hz and 2000 Hz, and 3 J emitted at a frequency of 2000 Hz caused a statistically significant loss of MSC viability. The applied photobiomodulation therapy induced a strong pro-apoptotic effect dependent on the laser irradiation exposure time, while the application of a sufficiently high-energy dose and frequency with a sufficiently long exposure time significantly increased intracellular calcium ion concentration and free radical production by MSCs.

Radiation-Induced Bystander Effect on the Genome of Bone Marrow Mesenchymal Stem Cells in Lung Cancer

Aims: Radiation by-radiation effect (RIBE) can induce the genomic instability of bone marrow mesenchymal stem cells (BMSCs) adjacent to lung cancer, and this effect not only exists in the short-term, but also accompanies it in the long-term, but its specific mechanism is not clear. Our goal is to explore the similarities and differences in the mechanism of genomic damage in tumor-associated BMSCs induced by short-term and long-term RIBE, and to provide a theoretical basis for adjuvant drugs for protection against RIBE at different clinical time periods. Results: We found that both short- and long-term RIBE induced genomic instability. We could show a high expression of TGF-β1, TNF-α, and HIF-1α in tumor-associated BMSCs after short-term RIBE whereas only TNF-α and HIF-1α expression was increased in long-term RIBE. We further confirmed that genomic instability is associated with the activation of the HIF-1α pathway and that this is mediated by TNF-α and TGF-β1. In addition, we found differences in the mechanisms of genomic instability in the considered RIBE windows of analysis. In short-term RIBE, both TNF-α and TGF-β1 play a role, whereas only TNF-α plays a decisive role in long-term RIBE. In addition, there were differences in BMSC recruitment and genomic instability of different tissues with a more pronounced expression in tumor and bone marrow than compared to lung. Innovation and Conclusion: We could show dynamic changes in the expression of the cytokines TGF-β1 and TNF-α during short- and long-term RIBE. The differential expression of the two is the key to causing the genomic damage of tumor-associated BMSCs in the considered windows of analysis. Therefore, these results may serve as a guideline for the administration of radiation protection adjuvant drugs at different clinical stages. Antioxid. Redox Signal. 38, 747-767.

Low-intensity pulsed ultrasound enhances bone marrow-derived stem cells-based periodontal regenerative therapies

BACKGROUND

Alveolar bone loss is one of the most common consequence for periodontitis, which is a major obstacle in periodontal regeneration. Bone marrow stromal cells (BMSCs) have shown significant promise in the treatment of various disease, which also contribute to the natural bone repair process. Low-intensity pulsed ultrasound (LIPUS) is a therapeutic ultrasound used in our previous studies to promotes alveolar bone regeneration. In addition, LIPUS was found to be a promising method to enhance mesenchymal stromal cell-based therapies. In the current study, we have investigated the effects of LIPUS combined with BMSCs therapies on BMSCs homing and its potential to promote alveolar bone regeneration.

METHODS

BMSCs were isolated from rat and characterized by multilineages differentiation assay. Then these cells were labeled with luciferase and green fluorescent protein (GFP) by lentivirus in vitro. Periodontal bone defect was made on the mesial area of the maxillary first molar in rats. A total of 1 × 10⁶ Luc-GFP labeled BMSCs were injected into rat tail vein. Bioluminescence imaging was utilized to track BMSCs in vivo. The rats were sacrificed eight weeks after surgery and the samples were harvested. Micro-computed tomography (Micro-CT) was performed to evaluate alveolar bone regeneration. Paraffin sections were made and subject to hematoxylin-eosin staining, masson staining and immunohistochemistry staining.

RESULTS

BMSCs display a fibroblast-like morphology and can differentiate into adipocytes or osteoblasts under appropriate condition. The transfected BMSCs are strongly positive for GFP express. Bioluminescence imaging showed that most of BMSCs were trapped in the lung. A small portion BMSCs were homed to the alveolar bone defect area in BMSCs group, while more cells were observed in BMSCs/LIPUS group compare to other groups on day 3 and 7. Micro-CT results showed that BMSCs/LIPUS group resulted in more new bone formation than other groups. Immunohistochemical results showed higher expression of COL-I and osteopontin in BMSCs/LIPUS group compared with the other groups.

CONCLUSIONS

These results suggested that LIPUS can enhance BMSCs-based periodontal alveolar bone regeneration. This study provides new insights into how LIPUS might provide therapeutic benefits by promoting BMSCs homing.

Fractionated Irradiation of Right Thorax Induces Abscopal Damage on Bone Marrow Cells via TNF-α and SAA

Radiation-induced abscopal effect (RIAE) outside of radiation field is becoming more attractive. However, the underlying mechanisms are still obscure. This work investigated the deleterious effect of thoracic irradiation (Th-IR) on distant bone marrow and associated signaling factors by irradiating the right thorax of mice with fractionated doses (8 Gy × 3). It was found that this localized Th-IR increased apoptosis of bone marrow cells and micronucleus formation of bone marrow polychromatic erythrocytes after irradiation. Tandem mass tagging (TMT) analysis and ELISA assay showed that the concentrations of TNF-α and serum amyloid A (SAA) in the mice were significantly increased after Th-IR. An immunohistochemistry assay revealed a robust increase in SAA expression in the liver rather than in the lungs after Th-IR. In vitro experiments demonstrated that TNF-α induced SAA expression in mouse hepatoma Hepa1-6 cells, and these two signaling factors induced DNA damage in bone marrow mesenchymal stem cells (BMSCs) by increasing reactive oxygen species (ROS). On the other hand, injection with TNF-α inhibitor before Th-IR reduced the secretion of SAA and attenuated the abscopal damage in bone marrow. ROS scavenger NAC could also mitigated Th-IR/SAA-induced bone marrow damage in mice. Our findings indicated that Th-IR triggered TNF-α release from lung, which further promoted SAA secretion from liver in a manner of cascade reaction. Consequently, these signaling factors resulted in induction of abscopal damage on bone marrow of mice.

Radiation-Induced Osteocyte Senescence Alters Bone Marrow Mesenchymal Stem Cell Differentiation Potential via Paracrine Signaling

Cellular senescence and its senescence-associated secretory phenotype (SASP) are widely regarded as promising therapeutic targets for aging-related diseases, such as osteoporosis. However, the expression pattern of cellular senescence and multiple SASP secretion remains unclear, thus leaving a large gap in the knowledge for a desirable intervention targeting cellular senescence. Therefore, there is a critical need to understand the molecular mechanism of SASP secretion in the bone microenvironment that can ameliorate aging-related degenerative pathologies including osteoporosis. In this study, osteocyte-like cells (MLO-Y4) were induced to cellular senescence by 2 Gy γ-rays; then, senescence phenotype changes and adverse effects of SASP on bone marrow mesenchymal stem cell (BMSC) differentiation potential were investigated. The results revealed that 2 Gy irradiation could hinder cell viability, shorten cell dendrites, and induce cellular senescence, as evidenced by the higher expression of senescence markers p16 and p21 and the elevated formation of senescence-associated heterochromatin foci (SAHF), which was accompanied by the enhanced secretion of SASP markers such as IL-1α, IL-6, MMP-3, IGFBP-6, resistin, and adiponectin. When 0.8 μM JAK1 inhibitors were added to block SASP secretion, the higher expression of SASP was blunted, but the inhibition in osteogenic and adipogenic differentiation potential of BMSCs co-cultured with irradiated MLO-Y4 cell conditioned medium (CM- 2 Gy) was alleviated. These results suggest that senescent osteocytes can perturb BMSCs’ differential potential via the paracrine signaling of SASP, which was also demonstrated by in vivo experiments. In conclusion, we identified the SASP factor partially responsible for the degenerative differentiation of BMSCs, which allowed us to hypothesize that senescent osteocytes and their SASPs may contribute to radiation-induced bone loss.

In vitro cellular and proteome assays identify Wnt pathway and CDKN2A-regulated senescence affected in mesenchymal stem cells from mice after a chronic LD gamma irradiation in utero

Reliable data on the effects of chronic prenatal exposure to low dose (LD) of ionizing radiation in humans are missing. There are concerns about adverse long-term effects that may persist throughout postnatal life of the offspring. Due to their slow cell cycle kinetics and life-long residence time in the organism, mesenchymal stem cells (MSCs) are more susceptible to low level genotoxic stress caused by extrinsic multiple LD events. The aim of this study was to investigate the effect of chronic, prenatal LD gamma irradiation to the biology of MSCs later in life. C3H mice were exposed in utero to chronic prenatal irradiation of 10 mGy/day over a period of 3 weeks. Two years later, MSCs were isolated from the bone marrow and analyzed in vitro for their radiosensitivity, for cellular senescence and for DNA double-strand break recognition after a second acute gamma-irradiation. In addition to these cellular assays, changes in protein expression were measured using HPLC-MS/MS and dysregulated molecular signaling pathways identified using bioinformatics. We observed radiation-induced proteomic changes in MSCs from the offspring of in utero irradiated mice (leading to ~ 9.4% of all detected proteins being either up- or downregulated) as compared to non-irradiated controls. The proteomic changes map to regulation pathways involved in the extracellular matrix, the response to oxidative stress, and the Wnt signaling pathway. In addition, chronic prenatal LD irradiation lead to an increased rate of in vitro radiation-induced senescence later in life and to an increased number of residual DNA double-strand breaks after 4 Gy irradiation, indicating a remarkable interaction of in vivo radiation in combination with a second acute dose of in vitro radiation. This study provides the first insight into a molecular mechanism of persistent MSC damage response by ionizing radiation exposure during prenatal time and will help to predict therapeutic safety and efficacy with respect to a clinical application of stem cells.

Photobiomodulation has rejuvenating effects on aged bone marrow mesenchymal stem cells

The plasticity and proliferative capacity of stem cells decrease with aging, compromising their tissue regenerative potential and therapeutic applications. This decline is directly linked to mitochondrial dysfunction. Here, we present an effective strategy to reverse aging of mouse bone marrow mesenchymal stem cells (BM-MSCs) by restoring their mitochondrial functionality using photobiomodulation (PBM) therapy. Following the characterization of young and aged MSCs, our results show that a near-infrared PBM treatment delivering 3 J/cm2 is the most effective modality for improving mitochondrial functionality and aging markers. Furthermore, our results unveil that young and aged MSCs respond differently to the same modality of PBM: whereas the beneficial effect of a single PBM treatment dissipates within 7 h in aged stem cells, it is lasting in young ones. Nevertheless, by applying three consecutive treatments at 24-h intervals, we were able to obtain a lasting rejuvenating effect on aged MSCs. Our findings are of particular significance for improving autologous stem cell transplantation in older individuals who need such therapies most.

Rspo1-LGR4 axis in BMSCs protects bone against radiation-induced injury through the mTOR-dependent autophagy pathway

While mesenchymal stem cells (MSCs) have been widely used to repair radiation-induced bone damage, the molecular mechanism underlying the effects of MSCs in the maintenance of bone homeostasis under radiation stress remains largely unknown. In this study, the role and mechanisms of R-spondin 1 (Rspo1)-leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4) axis on the initiation of self-defense of bone mesenchymal stem cells (BMSCs) and maintenance of bone homeostasis under radiation stress were investigated. Interestingly, radiation increased levels of Rspo1 and LGR4 in BMSCs. siRNA knockdown of Rspo1 or LGR4 aggravated radiation-induced impairment of self-renewal ability and osteogenic differentiation potential of BMSCs. However, exogenous Rspo1 significantly attenuated radiation-induced depletion of BMSCs, and promoted the lineage shift towards osteoblasts. This alteration was associated with the reversal of mammalian target of rapamycin (mTOR) activation and autophagy decrement. Pharmacological and genetic blockade of autophagy attenuated the radio-protective effects of Rspo1, rendering BMSCs more vulnerable to radiation-induced injury. Then bone radiation injury was induced in C57BL6J mice to further determine the radio-protective effects of Rspo1. In mice, administration of Rspo1 recombinant protein alleviated radiation-induced bone loss. Our results uncover that Rspo1-LGR4-mTOR-autophagy axis are key mechanisms by which BMSCs initiate self-defense against radiation and maintain bone homeostasis. Targeting Rspo1-LGR4 may provide a novel strategy for the intervention of radiation-induced bone damage.

Changes in ionizing radiation dose rate affect cell cycle progression in adipose derived stem cells

Biomedical use of radiation is utilized in effective diagnostic and treatment tools, yet can introduce risks to healthy tissues. High energy photons used for diagnostic purposes have high penetration depth and can discriminate multiple tissues based on attenuation properties of different materials. Likewise, the ability to deposit energy at various targets within tumors make the use of photons effective treatment for cancer. Radiation focused on a tumor will deposit energy when it interacts with a biological structure (e.g. DNA), which will result in cell kill should repair capacity of the tissue be overwhelmed. Likewise, damage to normal, non-cancerous tissues is a consequence of radiation that can lead to acute or late, chronic toxicity profiles. Adipose derived stem cells (ADSCs) are mesenchymal stem cells that have been proven to have similar characteristics to bone marrow derived stem cells, except that they are much easier to obtain. Within the body, ADSCs act as immunomodulators and assist with the maintenance and repair of tissues. They have been shown to have excellent differentiation capability, making them an extremely viable option for stem cell therapies and regenerative medicine applications. Due to the tissue ADSCs are derived from, they are highly likely to be affected by radiation therapy, especially when treating tumors localized to structures with relatively high ADSC content (eg., breast cancer). For this reason, the purpose behind this research is to better understand how ADSCs are affected by doses of radiation comparable to a single fraction of radiation therapy. We also measured the response of ADSCs to exposure at different dose rates to determine if there is a significant difference in the response of ADSCs to radiation therapy relevant doses of ionizing radiation. Our findings indicate that ADSCs exposed to Cesium (Cs 137)-gamma rays at a moderate dose of 2Gy and either a low dose rate (1.40Gy/min) or a high dose rate (7.31Gy/min) slow proliferation rate, and with cell cycle arrest in some populations. These responses ADSCs were not as marked as previously measured in other stem cell types. In addition, our results indicate that differences in dose rate in the Gy/min range typically utilized in small animal or cell irradiation platforms have a minimal effect on the function of ADSCs. The potential ADSCs have in the space of regenerative medicine makes them an ideal candidate for study with ionizing radiation, as they are one of the main cell types to promote tissue healing.

3D-printed individualized tooth-borne tissue retraction devices compared to conventional dental splints for head and neck cancer radiotherapy: a randomized controlled trial

BACKGROUND

Despite modern treatment techniques, radiotherapy (RT) in patients with head and neck cancer (HNC) may be associated with high rates of acute and late treatment-related toxicity. The most effective approach to reduce sequelae after RT is to avoid as best as possible healthy tissues and organs at risk from the radiation target volume. Even small geometric changes can lead to a significant dose reduction in normal tissue and better treatment tolerability. The major objective of the current study is to investigate 3D printed, tooth-borne tissue retraction devices (TRDs) compared to conventional dental splints for head and neck RT.

METHODS

In the current two-arm randomized controlled phase II trial, a maximum of 34 patients with HNC will be enrolled. Patients will receive either TRDs or conventional dental splints (randomization ratio 1:1) for the RT. The definition of the target volume, modality, total dose, fractionation, and imaging guidance is not study-specific. The primary endpoint of the study is the rate of acute radiation-induced oral mucositis after RT. The quality of life, local control and overall survival 12 months after RT are the secondary endpoints. Also, patient-reported outcomes and dental status, as well as RT plan comparisons and robustness analyzes, will be assessed as exploratory endpoints. Finally, mesenchymal stem cells, derived from the patients' gingiva, will be tested in vitro for regenerative and radioprotective properties.

DISCUSSION

The preliminary clinical application of TRD showed a high potential for reducing acute and late toxicity of RT in patients with HNC. The current randomized study is the first to prospectively investigate the clinical tolerability and efficacy of TRDs for radiation treatment of head and neck tumors.

TRIAL REGISTRATION

ClinicalTrials.gov; NCT04454697; July 1st 2020; https://clinicaltrials.gov/ct2/show/record/NCT04454697 .

Application of low-intensity pulsed therapeutic ultrasound on mesenchymal precursors does not affect their cell properties

Ultrasound is considered a safe and non-invasive tool in regenerative medicine and has been used in the clinic for more than twenty years for applications in bone healing after the approval of the Exogen device, also known as low-intensity pulsed ultrasound (LIPUS). Beyond its effects on bone health, LIPUS has also been investigated for wound healing of soft tissues, with positive results for various cell processes including cell proliferation, migration and angiogenesis. As LIPUS has the potential to treat chronic skin wounds, we sought to evaluate the effects produced by a conventional therapeutic ultrasound device at low intensities (also considered LIPUS) on the migration capacity of mouse and human skin mesenchymal precursors (s-MPs). Cells were stimulated for 3 days (20 minutes per day) using a traditional ultrasound device with the following parameters: 100 mW/cm2 with 20% duty cycle and frequency of 3 MHz. At the parameters used, ultrasound failed to affect s-MP proliferation, with no evident changes in morphology or cell groupings, and no changes at the cytoskeletal level. Further, the migration and invasion ability of s-MPs were unaffected by the ultrasound protocol, and no major changes were detected in the gene/protein expression of ROCK1, integrin β1, laminin β1, type I collagen and transforming growth factor β1. Finally, RNA-seq analysis revealed that only 10 genes were differentially expressed after ultrasound stimulation. Among them, 5 encode for small nuclear RNAs and 2 encode for proteins belonging to the nuclear pore complex. Considering the results overall, while the viability of s-MPs was not affected by ultrasound stimulation and no changes were detected in proliferation/migration, RNA-seq analysis would suggest that s-MPs do respond to ultrasound. The use of 100 mW/cm2 intensity or conventional therapeutic ultrasound devices might not be optimal for the stimulation the properties of cell populations. Future studies should investigate the potential application of ultrasound using variations of the tested parameters.

Impact of 2 Gy γ-irradiation on the hallmark characteristics of human bone marrow-derived MSCs

Two gray γ-irradiation is a widely employed basic module for total body irradiation (TBI) in allogeneic hematopoietic cell transplantation (HCT). The effects of γ-irradiation on hematopoietic and immune cells have been well investigated, but its effects on the bone marrow microenvironment (BMM) are unknown. Given the crucial contribution of mesenchymal/stromal stem cells (MSCs) in the BMM to hematopoiesis and osteogenesis, we investigated whether γ-irradiation affects the hallmark characteristics of human bone marrow-derived MSCs (BM-MSCs). Expansion of 2 Gy γ-irradiated BM-MSCs was delayed but eventually recovered. Colony formation and osteogenic, adipogenic, and chondrogenic differentiation capabilities of these cells were extensively suppressed. Irradiation of BM-MSCs did not affect the expansion of CD34 + hematopoietic stem and progenitor cells or production of CD11b + mature myeloid cells in co-cultures. However, it reduced production of CD19 + B-cells, as well as expression of CXCL12 and interleukin-7, which are essential for B-cell lymphopoiesis, in 2 Gy γ-irradiated BM-MSCs. Collectively, colony formation, osteogenic differentiation, and B-cell lymphopoiesis-supportive capabilities of γ-irradiated BM-MSCs were reduced. These effects may predispose survivors receiving HCT with TBI to defective bone formation and a perturbed humoral immune response.

The effects of 808-nm near-infrared laser light irradiation on actin cytoskeleton reorganization in bone marrow mesenchymal stem cells

Tailoring the cell organelles and thus changing cell homeostatic behavior has permitted the discovery of fascinating metabolic features enabling enhanced viability, differentiation, or quenching inflammation. Recently, photobiomodulation (PBM) has been accredited as an effective cell manipulation technique with promising therapeutic potential. In this prospective, in vitro results revealed that 808-nm laser light emitted by a hand-piece with a flat-top profile at an irradiation set up of 60 J/cm2 (1 W, 1 W/cm²; 60 s, continuous wave) regulates bone marrow stromal cell (BMSC) differentiation toward osteogenesis. Considering the importance of actin cytoskeleton reorganization, which controls a range of cell metabolic activities, comprising shape change, proliferation and differentiation, the aim of the current work is to assess whether PBM therapy, using a flat-top hand-piece at higher-fluence irradiation on BMSCs, is able to switch photon signals into the stimulation of biochemical/differentiating pathways involving key activators that regulate de novo actin polymerization. Namely, for the first time, we unearthed the role of the flat-top hand-piece at higher-fluence irradiation on cytoskeletal characteristics of BMSCs. These novel findings meet the needs of novel therapeutically protocols provided by laser treatment and the manipulation of BMSCs as anti-inflammatory, osteo-inductive platforms.

Rationale for the Use of Radiation-Activated Mesenchymal Stromal/Stem Cells in Acute Respiratory Distress Syndrome

We have previously shown that the combination of radiotherapy with human umbilical-cord-derived mesenchymal stromal/stem cells (MSCs) cell therapy significantly reduces the size of the xenotumors in mice, both in the directly irradiated tumor and in the distant nonirradiated tumor or its metastasis. We have also shown that exosomes secreted from MSCs preirradiated with 2 Gy are quantitatively, functionally and qualitatively different from the exosomes secreted from nonirradiated mesenchymal cells, and also that proteins, exosomes and microvesicles secreted by MSCs suffer a significant change when the cells are activated or nonactivated, with the amount of protein present in the exosomes of the preirradiated cells being 1.5 times greater compared to those from nonirradiated cells. This finding correlates with a dramatic increase in the antitumor activity of the radiotherapy when is combined with MSCs or with preirradiated mesenchymal stromal/stem cells (MSCs*). After the proteomic analysis of the load of the exosomes released from both irradiated and nonirradiated cells, we conclude that annexin A1 is the most important and significant difference between the exosomes released by the cells in either status. Knowing the role of annexin A1 in the control of hypoxia and inflammation that is characteristic of acute respiratory-distress syndrome (ARDS), we designed a hypothetical therapeutic strategy, based on the transplantation of mesenchymal stromal/stem cells stimulated with radiation, to alleviate the symptoms of patients who, due to pneumonia caused by SARS-CoV-2, require to be admitted to an intensive care unit for patients with life-threatening conditions. With this hypothesis, we seek to improve the patients' respiratory capacity and increase the expectations of their cure.

Magnetic Stimulation Drives Macrophage Polarization in Cell to-Cell Communication with IL-1β Primed Tendon Cells

Inflammation is part of the natural healing response, but it has been simultaneously associated with tendon disorders, as persistent inflammatory events contribute to physiological changes that compromise tendon functions. The cellular interactions within a niche are extremely important for healing. While human tendon cells (hTDCs) are responsible for the maintenance of tendon matrix and turnover, macrophages regulate healing switching their functional phenotype to environmental stimuli. Thus, insights on the hTDCs and macrophages interactions can provide fundamental contributions on tendon repair mechanisms and on the inflammatory inputs in tendon disorders. We explored the crosstalk between macrophages and hTDCs using co-culture approaches in which hTDCs were previously stimulated with IL-1β. The potential modulatory effect of the pulsed electromagnetic field (PEMF) in macrophage-hTDCs communication was also investigated using the magnetic parameters identified in a previous work. The PEMF influences a macrophage pro-regenerative phenotype and favors the synthesis of anti-inflammatory mediators. These outcomes observed in cell contact co-cultures may be mediated by FAK signaling. The impact of the PEMF overcomes the effect of IL-1β-treated-hTDCs, supporting PEMF immunomodulatory actions on macrophages. This work highlights the relevance of intercellular communication in tendon healing and the beneficial role of the PEMF in guiding inflammatory responses toward regenerative strategies.

Ceria-Containing Hybrid Multilayered Microcapsules for Enhanced Cellular Internalisation with High Radioprotection Efficiency

Cerium oxide nanoparticles (nanoceria) are believed to be the most versatile nanozyme, showing great promise for biomedical applications. At the same time, the controlled intracellular delivery of nanoceria remains an unresolved problem. Here, we have demonstrated the radioprotective effect of polyelectrolyte microcapsules modified with cerium oxide nanoparticles, which provide controlled loading and intracellular release. The optimal (both safe and uptake efficient) concentrations of ceria-containing microcapsules for human mesenchymal stem cells range from 1:10 to 1:20 cell-to-capsules ratio. We have revealed the molecular mechanisms of nanoceria radioprotective action on mesenchymal stem cells by assessing the level of intracellular reactive oxygen species (ROS), as well as by a detailed 96-genes expression analysis, featuring genes responsible for oxidative stress, mitochondrial metabolism, apoptosis, inflammation etc. Hybrid ceria-containing microcapsules have been shown to provide an indirect genoprotective effect, reducing the number of cytogenetic damages in irradiated cells. These findings give new insight into cerium oxide nanoparticles' protective action for living beings against ionising radiation.

Photothermal modulation of human stem cells using light-responsive 2D nanomaterials

Two-dimensional (2D) molybdenum disulfide (MoS2) nanomaterials are an emerging class of biomaterials that are photoresponsive at near-infrared wavelengths (NIR). Here, we demonstrate the ability of 2D MoS2 to modulate cellular functions of human stem cells through photothermal mechanisms. The interaction of MoS2 and NIR stimulation of MoS2 with human stem cells is investigated using whole-transcriptome sequencing (RNA-seq). Global gene expression profile of stem cells reveals significant influence of MoS2 and NIR stimulation of MoS2 on integrins, cellular migration, and wound healing. The combination of MoS2 and NIR light may provide new approaches to regulate and direct these cellular functions for the purposes of regenerative medicine as well as cancer therapy.

Elevation of CXCL1 indicates poor prognosis and radioresistance by inducing mesenchymal transition in glioblastoma

INTRODUCTION

Glioblastoma (GBM) is identified as a lethal malignant tumor derived from the nervous system. Despite the standard clinical strategy including maximum surgical resection, temozolomide (TMZ) chemotherapy, and radiotherapy, the median survival of GBM patients remains <15 months. Accumulating evidence indicates that rapid-acquired radioresistance is one of the most common reasons for GBM recurrence. Therefore, developing novel therapeutic targets for radioresistant GBM could yield long-term cures.

AIMS

To investigate the functional role of CXCL1 in the acquired radioresistance and identify the molecular pathway correlated to CXCL1.

RESULTS

In this study, we identified that CXCL1 is highly expressed in GBM and the elevation of CXCL1 is involved in radioresistance and poor prognosis in GBM patients. Additionally, silencing CXCL1 attenuated the proliferation and radioresistance of GBM cells. Furthermore, we demonstrated that CXCL1-overexpression induced radioresistance through mesenchymal transition of GBM via the activation of nuclear factor-kappa B (NF-κB) signaling.

CONCLUSION

CXCL1 was highly enriched in GBM and positively correlated with poor prognosis in GBM patients. Additionally, elevated CXCL1 induced radioresistance in GBM through regulation of NF-κB signaling by promoting mesenchymal transition in GBM.

Intraoperative radiotherapy for breast cancer treatment efficiently targets the tumor bed preventing breast adipose stromal cell outgrowth

OBJECTIVES

Mesenchymal stromal cells (MSC) in bone marrow have been shown to be radioresistant, which is related to pronounced DNA repair mechanisms. Intraoperative radiotherapy (IORT) during breast-conserving surgery for early breast cancer is an innovative technique applying low energy x‑ray to the tumor bed immediately after removal of the tumor. IORT is considered to reduce the risk of local tumor recurrence by directly targeting cells of the tumor bed and altering the local microenvironment. Aim of this study was to investigate whether IORT affects the outgrowth potential of breast adipose tissue-derived MSC (bASC) as part of the tumor bed.

MATERIALS AND METHODS

After surgical tumor resection, biopsies of the tumor bed were taken before (pre IORT) and after IORT (post IORT) and processed applying well-established protocols for ASC isolation and characterization.

RESULTS

In all, 95% of pre IORT tumor bed samples yielded persistently outgrowing bASC with typical ASC characteristics: fibroblastoid morphology, proliferation, adipogenic and osteogenic differentiation and ASC surface marker expression. However, none of the post IORT samples yielded persistent outgrowth of bASC.

CONCLUSIONS

After breast-conserving surgery, approximately 90% of local recurrences emerge in close proximity to the initial tumor bed, potentially reflecting a significant contribution of the tumor bed to relapse. Our data show that IORT, besides the proven effect on breast cancer cells, efficiently modifies the tumor environment by having an impact on tumor bed bASC. This effect on tumor bed stromal cells might contribute to reduce the risk of tumor relapse and metastases.

Nrf2 played an important role in radiation protection effect of low-level laser exposed on umbilical cord mesenchymal stem cell

To investigate the protective function of low-level laser irradiation (LLLI) against ionizing irradiation and explore the molecular mechanism of photomodulation of Nrf2 protein, the impact of LLLI (635 nm, 5.7 J/cm²) before 2 Gy gamma ray radiation of radio-sensitive tissue hematopoietic stem cells was evaluated. As a result, reduced levels of reactive oxygen species and increased expression of antioxidant enzymes were detected. Moreover, increased expression of Nrf2 was observed after LLLI, whereas brusatol pretreatment before LLLI abolished this effect. In vivo, transplantation of human umbilical cord mesenchymal stem cells (hUC-MSCs) was employed for therapy of hematopoietic function in an acute radiation sickness (H-ARS) mouse model, which was induced by 6-Gy ionizing irradiation; different hUC-MSC pretreatments including LLLI and Nrf2 RNAi were accounted for during experimental grouping. LLLI treatment of cells significantly increased the erythrocyte count and number of myelopoiesis clones (P < 0.05), but such improvements were reduced by Nrf2 RNAi pretreatment compared with cells transplanted without intervention. Therefore, LLLI may improve the radiation protection effect through molecular mechanisms related to the Nrf2 antioxidant pathway.

First Insights into the Effect of Low-Dose X-Ray Irradiation in Adipose-Derived Stem Cells

(1) Background: Emerging interest of physicians to use adipose-derived stem cells (ADSCs) for regenerative therapies and the fact that low-dose irradiation (LD-IR ≤ 0.1 Gy) has been reported to enhance the proliferation of several human normal and bone-marrow stem cells, but not that of tumor cells, lead to the idea of improving stem cell therapies via low-dose radiation. Therefore, the aim of this study was to investigate unwanted side effects, as well as proliferation-stimulating mechanisms of LD-IR on ADSCs. (2) Methods: To avoid donor specific effects, ADSCs isolated from mamma reductions of 10 donors were pooled and used for the radiobiological analysis. The clonogenic survival assay was used to classify the long-term effects of low-dose radiation in ADSCs. Afterwards, cytotoxicity and genotoxicity, as well as the effect of irradiation on proliferation of ADSCs were investigated. (3) Results: LD (≤ 0.1 Gy) of ionizing radiation promoted the proliferation and survival of ADSCs. Within this dose range neither geno- nor cytotoxic effects were detectable. In contrast, greater doses within the dose range of >0.1–2.0 Gy induced residual double-strand breaks and reduced the long-term survival, as well as the proliferation rate of ADSCs. (4) Conclusions: Our data suggest that ADSCs are resistant to LD-IR. Furthermore, LD-IR could be a possible mediator to improve approaches of stem cells in the field of regenerative medicine.

Influence of electromagnetic waves, with maxima in the green or red range, on the morphofunctional properties of multipotent stem cells

This paper examines the effect of electromagnetic waves, with maxima in the green or red regions of the spectrum, on the morphofunctional state of multipotent mesenchymal stromal cells. The illumination regimes used in our experiments did not lead to any substantial heating of the samples; the physical parameters of the lighting were carefully monitored. When the samples were illuminated with a green light, no significant photostimulatory effect was observed. Red light, on the other hand, had an evident photostimulatory effect. It is shown that photostimulation with a red light decreases the enzymatic activities of mitochondrial dehydrogenases and enhances the viability of cells, their proliferative activity, and their ability to form bone tissue. It is also established that red light stimulates cell proliferation, while not activating the genes that increase the risk of the subsequent malignant transformation of cells or their death. This paper discusses the possible role of hydrogen peroxide in the processes examined.

Dynamic Titania Nanotube Surface Achieves UV-Triggered Charge Reversal and Enhances Cell Differentiation

Stimuli-responsive biomaterials supply a promising solution to adapt to the complex physiological environment for different biomedical applications. In this study, a dynamic UV-triggered pH-responsive biosurface was constructed on titania nanotubes (TNTs) by loading photoacid generators, diphenyliodonium chloride, into the nanotubes, and grafting 2,3-dimethyl maleic anhydride (DMMA)-modified hyperbranched poly(l-lysine) (HBPLL) onto the surface. The local acidity was dramatically enhanced by UV irradiation for only 30 s, leading to the dissociation of DMMA and thereby the transformation of surface chemistry from negatively charged caboxyl groups to positively charged amino groups. The TNTs-HBPLL-DMMA substrate could better promote proliferation and spreading of rat bone mesenchymal stem cells (rBMSCs) after UV irradiation. The osteogenic differentiation of rBMSCs was enhanced because of the charge reversal in combination with the titania-based substrates.

Enhanced osteogenesis of bone marrow stem cells cultured on hydroxyapatite/collagen I scaffold in the presence of low-frequency magnetic field

As a non-invasive biophysical therapy, electromagnetic fields (EMF) have been widely used to promote the healing of fractures. In the present study, hydroxyapatite/collagen I (HAC) loaded with rabbit bone marrow mesenchymal stem cells (MSCs) were cultured in a dynamic perfusion bioreactor and exposed to EMF of 15 Hz/1mT. Osteogenic differentiation of the seeded cells was analyzed through the evaluation of ALP activity and osteogenesis-related genes expression in vitro. The in vivo osteogenesis efficacy of the cell laden HAC constructs treated with/without EMF was evaluated through a rabbit femur condyle defect model. The results showed that EMF of 15 Hz/1mT could enhance the osteogenic differentiation of the cells seeded on HAC scaffold. Furthermore, the in vivo experiments demonstrated that EMF exposure could promote bone regeneration within the defect and bone integration between the graft and host bone. Taking together, the MSCs seeded HAC scaffold combined with EMF exposure could be a promising approach for bone tissue engineering.

The response of human mesenchymal stem cells to internal exposure to tritium β-rays

There is no doubt that estimating the exposure risk of external and internal low-dose radiation is an imperative issue in radiobiological study. Human mesenchymal stem cells (hMSCs) are multipotent and self-renewing, supporting the regeneration of damaged tissue, including tissue damaged by radiation. However, the responses of hMSCs to internal exposure to radionuclides are still insufficiently understood. In order to evaluate the adverse effects produced by internal exposure to tritiated water (HTO) at a low dose, hMSCs were exposed to 2 × 107 Bq/ml HTO, and the biological effects after the exposure were examined. Apoptosis and DNA double-strand breaks (DSBs) were assayed to analyze the cellular response to the damage induced by HTO. Slight enhancement of apoptosis was found after treatment, except at the dose of 9 mGy. The number of DSBs at 24 h post-irradiation showed that the DNA damage was able to be efficiently repaired by the hMSCs. Moreover, the increasing proportion of the cell population in S phase proved that the persistence of residual γH2AX foci at lower concentrations of HTO was attributable to the secondary production of DSBs in DNA replication. Our work adds to the available data, helping us understand the risk of stem cell transformation due to internal exposure and its correlation with low-dose radiation-induced carcinogenesis.

Formation of γH2AX and pATM Foci in Human Mesenchymal Stem Cells Exposed to Low Dose-Rate Gamma-Radiation

DNA double-strand breaks (DSB) are among the most harmful DNA lesions induced by ionizing radiation (IR). Although the induction and repair of radiation-induced DSB is well studied for acute irradiation, responses to DSB produced by chronic IR exposures are poorly understood, especially in human stem cells. The aim of this study was to examine the formation of DSB markers (γH2AX and phosphorylated kinase ATM, pATM, foci) in human mesenchymal stem cells (MSCs) exposed to chronic gamma-radiation (0.1 mGy/min) in comparison with acute irradiation (30 mGy/min) at cumulative doses of 30, 100, 160, 240 and 300 mGy. A linear dose-dependent increase in the number of both γH2AX and pATM foci, as well as co-localized γH2AX/pATM foci ("true" DSB), were observed after an acute radiation exposure. In contrast, the response of MSCs to a chronic low dose-rate IR exposure deviated from linearity towards a threshold model, for γH2AX, pATM foci and γH2AX/pATM foci, with an indication of a "plateau". The state of equilibrium between newly formed DSB at a low rate during the protracted exposure time and the elimination of a fraction of DSB is proposed as a mechanistic explanation of the non-linear DSB responses following a low dose-rate irradiation. This notion is supported by the observation of the elimination of a substantial fraction of DSB 6 h after the cessation of the exposures. Our results demonstrate non-linear dose responses for γH2AX and pATM foci in human MSCs exposed to low dose-rate IR and showed the existence of a threshold, which may have implications for radiation protection in humans.

miR-31-5p Is a LIPUS-Mechanosensitive MicroRNA that Targets HIF-1α Signaling and Cytoskeletal Proteins

The roles of low-intensity pulsed ultrasound (LIPUS) and microRNAs (miRNAs) on hMSCs commitments have already been investigated; however, the effects of the application of their co-treatments in an in vitro cell model are still unknown. Our previous studies demonstrated that (i) LIPUS modulated hMSCs cytoskeletal organization and (ii) miRNA-675-5p have a role in HIF-1α signaling modulation during hMSCs osteoblast commitment. We investigated for the first time the role of LIPUS as promoter tool for miRNA expression. Thanks to bioinformatic analysis, we identified miR-31-5p as a LIPUS-induced miRNA and investigated its role through in vitro studies of gain and loss of function. Results highlighted that LIPUS stimulation induced a hypoxia adaptive cell response, which determines a reorganization of cell membrane and cytoskeleton proteins. MiR-31-5p gain and loss of function studies, demonstrated as miR-31-5p overexpression, were able to induce hypoxic and cytoskeletal responses. Moreover, the co-treatments LIPUS and miR-31-5p inhibitor abolished the hypoxic responses including angiogenesis and the expression of Rho family proteins. MiR-31-5p was identified as a LIPUS-mechanosensitive miRNAs and may be considered a new therapeutic option to promote or abolish hypoxic response and cytoskeletal organization on hMSCs during the bone regeneration process.

Simultaneous cell traction and growth measurements using light

Characterizing the effects of force fields generated by cells on proliferation, migration and differentiation processes is challenging due to limited availability of nondestructive imaging modalities. Here, we integrate a new real-time traction stress imaging modality, Hilbert phase dynamometry (HPD), with spatial light interference microscopy (SLIM) for simultaneous monitoring of cell growth during differentiation processes. HPD uses holographic principles to extract displacement fields from chemically patterned fluorescent grid on deformable substrates. This is converted into forces by solving an elasticity inverse problem. Since HPD uses the epi-fluorescence channel of an inverted microscope, cellular behavior can be concurrently studied in transmission with SLIM. We studied the differentiation of mesenchymal stem cells (MSCs) and found that cells undergoing osteogenesis and adipogenesis exerted larger and more dynamic stresses than their precursors, with MSCs developing the smallest forces and growth rates. Thus, we develop a powerful means to study mechanotransduction during dynamic processes where the matrix provides context to guide cells toward a physiological or pathological outcome.

Photobiomodulation with single and combination laser wavelengths on bone marrow mesenchymal stem cells: proliferation and differentiation to bone or cartilage

Tissue engineering aims to take advantage of the ability of undifferentiated stem cells to differentiate into multiple cell types to repair damaged tissue. Photobiomodulation uses either lasers or light-emitting diodes to promote stem cell proliferation and differentiation. The present study aimed to investigate single and dual combinations of laser wavelengths on mesenchymal stem cells (MSCs). MSCs were derived from rabbit iliac bone marrow. One control and eight laser irradiated groups were designated as Infrared (IR, 810 nm), Red (R, 660 nm), Green (G, 532 nm), Blue (B, 485 nm), IR-R, IR-B, R-G, and B-G. Irradiation was repeated daily for 21 days and cell proliferation, osseous, or cartilaginous differentiation was then measured. RT-PCR biomarkers were SOX9, aggrecan, COL 2, and COL 10 expression for cartilage and ALP, COL 1, and osteocalcin expression for bone. Cellular proliferation was increased in all irradiated groups except G. All cartilage markers were significantly increased by IR and IR-B except COL 10 which was suppressed by IR-B combination. ALP expression was highest in R and IR groups during osseous differentiation. ALP was decreased by combinations of IR with B and with R, and also by G alone. R and B-G groups showed stimulated COL 1 expression; however, COL 1 was suppressed in IR-B, IR-R, and G groups. IR significantly increased osteocalcin expression, but in B, B-G, and G groups it was reduced. Cartilage differentiation was stimulated by IR and IR-B laser irradiation. The effects of single or combined laser irradiation were not clear-cut on osseous differentiation. Stimulatory effects on osteogenesis were seen for R and IR lasers, while G laser had inhibitory effects.

Role of NF-κB activation in mouse bone marrow stromal cells exposed to 900-MHz radiofrequency fields (RF)

Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a primary transcription factor which plays a key role in several cellular processes including proliferation and survival. It is well known that exposure to non-ionizing radiofrequency fields (RFs), which are ubiquitous, resulted in interaction with cellular components. The aim of the study was thus to examine whether exposure of mouse bone marrow stromal cells (BMSC) to RF also resulted in cellular interactions. BMSC were exposed to 900 MHz RF at 120 μW/cm² power intensity for 4 hr/day for 5 consecutive days. The relative protein expression levels of NF-κB in the cytoplasm and nucleus of RF-exposed cells were compared to non-RF-exposed controls. At 30-min post-RF exposure, a significant decrease in protein expression of NF-κB in the cytoplasm was accompanied by a concomitant increase in nuclear NF-κB protein expression levels. Similar responses were noted in the cytoplasm and nuclear NF-κB levels at 2 hr with a return to control concentrations in primary transcription factor at 24-hr post-RF treatment. Daily incubation of BAY 11-7082, an inhibitor of NF-κB, for 90 min for 5 days followed by RF each day prevented the fall in cytoplasmic NF-κB and rise in nuclear primary transcription factor at 30 min and 2 hr. There were no marked alterations at 24 hr. Data showed that the effects of RF treatment on BMSC involved transient activation of NF-κB which may be attributed to RF-mediated cellular perturbation as evidenced by consequences of BAY 11-7082 inhibition.

Radiation resistance of normal human astrocytes: the role of non-homologous end joining DNA repair activity

Radiotherapy is a common modality for treatment of brain cancers, but it can induce long-term physiological and cognitive deficits. The responses of normal human brain cells to radiation is not well understood. Astrocytes have been shown to have a variety of protective mechanisms against oxidative stress and have been shown to protect neurons. We investigated the response of cultured normal human astrocytes (NHAs) to X-ray irradiation. Following exposure to 10 Gy X-irradiation, NHAs exhibited DNA damage as indicated by the formation of γ-H2AX foci. Western blotting showed that NHAs displayed a robust increase in expression of non-homologous end joining DNA repair enzymes within 15 min post-irradiation and increased expression of homologous recombination DNA repair enzymes ~2 h post-irradiation. The cell cycle checkpoint protein p21/waf1 was upregulated from 6-24 h, and then returned to baseline. Levels of DNA repair enzymes returned to basal ~48 h post-irradiation. NHAs re-entered the cell cycle and proliferation was observed at 6 days. In contrast, normal human mesenchymal stem cells (MSCs) failed to upregulate DNA repair enzymes and instead displayed sustained upregulation of p21/waf1, a cell cycle checkpoint marker for senescence. Ectopic overexpression of Ku70 was sufficient to protect MSCs from sustained upregulation of p21/waf1 induced by 10 Gy X-rays. These findings suggest that increased expression of Ku70 may be a key mechanism for the radioresistance of NHAs, preventing their accelerated senescence from high-dose radiation. These results may have implications for the development of novel targets for radiation countermeasure development.

Comparative Analysis of the Formation of γH2AX Foci in Human Mesenchymal Stem Cells Exposed to 3H-Thymidine, Tritium Oxide, and X-Rays Irradiation

We performed a comparative study of the formation of γН2АХ foci (a marker of DNA doublestrand breaks) in human bone marrow mesenchymal stem cells after 24-h incubation with ³Н-thimidin and tritium oxide with low specific activities (50-800 MBq/liter). The dependence of the number of γH2AX foci on specific activity of 3H-thymidine was described by a linear equation y=2.21+43.45x (R²=0.96), where y is the number of γH2AX foci per nucleus and x is specific activity in 1000 MBq/liter. For tritium oxide, the relationship was described by a linear equation y=2.52+6.70x (R²=0.97). Thus, the yield of DNA double-strand breaks after exposure to ³H-thymidine was 6.5-fold higher than after exposure to tritium oxide. Comparison of the effects of tritium oxide and X-ray radiation on the yield of DNA double-strand breaks showed that the relative biological efficiency of tritium oxide in a dose range of 3.78-60.26 mGy was 1.6-fold higher than that of X-ray radiation. Improvement of the methods of analysis of DNA double-strand breaks repair foci is highly promising in the context of creation of highly sensitive biodosimetry technologies for tritium compounds in humans.

Improving hematopoietic recovery through modeling and modulation of the mesenchymal stromal cell secretome

BACKGROUND

Efficient and sustained hematopoietic recovery after hematopoietic stem cell or bone marrow transplantation is supported by paracrine signaling from specific subpopulations of mesenchymal stromal cells (MSCs). Here, we considered whether in vitro mechanopriming of human MSCs could be administered to predictively and significantly improve in vivo hematopoietic recovery after irradiation injury.

METHODS

First, we implemented regression modeling to identify eight MSC-secreted proteins that correlated strongly with improved rescue from radiation damage, including hematopoietic recovery, in a murine model of hematopoietic failure. Using these partial least squares regression (PLSR) model parameters, we then predicted recovery potential of MSC populations that were culture expanded on substrata of varying mechanical stiffness. Lastly, we experimentally validated these predictions using an in vitro co-culture model of hematopoiesis and using new in vivo experiments for the same irradiation injury model used to generate survival predictions.

RESULTS

MSCs grown on the least stiff (elastic moduli ~ 1 kPa) of these polydimethylsiloxane (PDMS) substrata secreted high concentrations of key proteins identified in regression modeling, at concentrations comparable to those secreted by minor subpopulations of MSCs shown previously to be effective in supporting such radiation rescue. We confirmed that these MSCs expanded on PDMS could promote hematopoiesis in an in vitro co-culture model with hematopoietic stem and progenitor cells (HSPCs). Further, MSCs cultured on PDMS of highest stiffness (elastic moduli ~ 100 kPa) promoted expression of CD123+ HSPCs, indicative of myeloid differentiation. Systemic administration of mechanoprimed MSCs resulted in improved mouse survival and weight recovery after bone marrow ablation, as compared with both standard MSC expansion on stiffer materials and with biophysically sorted MSC subpopulations. Additionally, we observed recovery of white blood cells, platelets, and red blood cells, indicative of complete recovery of all hematopoietic lineages.

CONCLUSIONS

These results demonstrate that computational techniques to identify MSC biomarkers can be leveraged to predict and engineer therapeutically effective MSC phenotypes defined by mechanoprimed secreted factors, for translational applications including hematopoietic recovery.

Aging of lymphoid organs: Can photobiomodulation reverse age-associated thymic involution via stimulation of extrapineal melatonin synthesis and bone marrow stem cells?

Thymic atrophy and the subsequent reduction in T-cell production are the most noticeable age-related changes affecting lymphoid organs in the immune system. In fact, thymic involution has been described as "programmed aging." New therapeutic approaches, such as photobiomodulation (PBM), may reduce or reverse these changes. PBM (also known as low-level laser therapy) involves the delivery of non-thermal levels of red or near-infrared light that are absorbed by mitochondrial chromophores, in order to prevent tissue death and stimulate healing and regeneration. PBM may reverse or prevent thymic involution due to its ability to induce extrapineal melatonin biosynthesis via cyclic adenosine monophosphate (AMP) or NF-kB activation, or alternatively by stimulating bone marrow stem cells that can regenerate the thymus. This perspective puts forward a hypothesis that PBM can alter thymic involution, improve immune functioning in aged people and even extend lifespan.

Red (635 nm), Near-Infrared (808 nm) and Violet-Blue (405 nm) Photobiomodulation Potentiality on Human Osteoblasts and Mesenchymal Stromal Cells: A Morphological and Molecular In Vitro Study

Photobiomodulation (PBM) has been used for bone regenerative purposes in different fields of medicine and dentistry, but contradictory results demand a skeptical look for its potential benefits. This in vitro study compared PBM potentiality by red (635 ± 5 nm) or near-infrared (NIR, 808 ± 10 nm) diode lasers and violet-blue (405 ± 5 nm) light-emitting diode operating in a continuous wave with a 0.4 J/cm² energy density, on human osteoblast and mesenchymal stromal cell (hMSC) viability, proliferation, adhesion and osteogenic differentiation. PBM treatments did not alter viability (PI/Syto16 and MTS assays). Confocal immunofluorescence and RT-PCR analyses indicated that red PBM (i) on both cell types increased vinculin-rich clusters, osteogenic markers expression (Runx-2, alkaline phosphatase, osteopontin) and mineralized bone-like nodule structure deposition and (ii) on hMSCs induced stress fiber formation and upregulated the expression of proliferation marker Ki67. Interestingly, osteoblast responses to red light were mediated by Akt signaling activation, which seems to positively modulate reactive oxygen species levels. Violet-blue light-irradiated cells behaved essentially as untreated ones and NIR irradiated ones displayed modifications of cytoskeleton assembly, Runx-2 expression and mineralization pattern. Although within the limitations of an in vitro experimentation, this study may suggest PBM with 635 nm laser as potential effective option for promoting/improving bone regeneration.

The effect of pulsed electromagnetic field exposure on osteoinduction of human mesenchymal stem cells cultured on nano-TiO2 surfaces

Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) are considered a great promise in the repair and regeneration of bone. Considerable efforts have been oriented towards uncovering the best strategy to promote stem cells osteogenic differentiation. In previous studies, hBM-MSCs exposed to physical stimuli such as pulsed electromagnetic fields (PEMFs) or directly seeded on nanostructured titanium surfaces (TiO₂) were shown to improve their differentiation to osteoblasts in osteogenic condition. In the present study, the effect of a daily PEMF-exposure on osteogenic differentiation of hBM-MSCs seeded onto nanostructured TiO₂ (with clusters under 100 nm of dimension) was investigated. TiO₂-seeded cells were exposed to PEMF (magnetic field intensity: 2 mT; intensity of induced electric field: 5 mV; frequency: 75 Hz) and examined in terms of cell physiology modifications and osteogenic differentiation. Results showed that PEMF exposure affected TiO₂-seeded cells osteogenesis by interfering with selective calcium-related osteogenic pathways, and greatly enhanced hBM-MSCs osteogenic features such as the expression of early/late osteogenic genes and protein production (e.g., ALP, COL-I, osteocalcin and osteopontin) and ALP activity. Finally, PEMF-treated cells resulted to secrete into conditioned media higher amounts of BMP-2, DCN and COL-I than untreated cell cultures. These findings confirm once more the osteoinductive potential of PEMF, suggesting that its combination with TiO₂ nanostructured surface might be a great option in bone tissue engineering applications.

External Beam Radiation Therapy Enhances Mesenchymal Stem Cell-Mediated Sodium-Iodide Symporter Gene Delivery

The tumor-homing properties of mesenchymal stem cells (MSC) have led to their development as delivery vehicles for the targeted delivery of therapeutic genes such as the sodium-iodide symporter (NIS) to solid tumors. External beam radiation therapy may represent an ideal setting for the application of engineered MSC-based gene therapy, as tumor irradiation may enhance MSC recruitment into irradiated tumors through the increased production of select factors linked to MSC migration. In the present study, the irradiation of human liver cancer cells (HuH7; 1-10 Gy) showed a strong dose-dependent increase in steady-state mRNA levels of CXCL8, CXCL12, FGF2, PDGFB, TGFB1, THBS1, and VEGF (0-48 h), which was verified for most factors at the protein level (after 48 h). Radiation effects on directed MSC migration were tested in vitro using a live cell tracking migration assay and supernatants from control and irradiated HuH7 cells. A robust increase in mean forward migration index, mean center of mass, and mean directionality of MSCs toward supernatants was seen from irradiated as compared to non-irradiated tumor cells. Transferability of this effect to other tumor sources was demonstrated using the human breast adenocarcinoma cell line (MDA-MB-231), which showed a similar behavior to radiation as seen with HuH7 cells in quantitative polymerase chain reaction and migration assay. To evaluate this in a more physiologic in vivo setting, subcutaneously growing HuH7 xenograft tumors were irradiated with 0, 2, or 5 Gy followed by CMV-NIS-MSC application 24 h later. Tumoral iodide uptake was monitored using ¹²³I-scintigraphy. The results showed increased tumor-specific dose-dependent accumulation of radioiodide in irradiated tumors. The results demonstrate that external beam radiation therapy enhances the migratory capacity of MSCs and may thus increase the therapeutic efficacy of MSC-mediated NIS radionuclide therapy.

Bone marrow-derived mesenchymal stromal cells promote colorectal cancer cell death under low-dose irradiation

BACKGROUND

Radiotherapy remains one of the cornerstones to improve the outcome of colorectal cancer (CRC) patients. Radiotherapy of the CRC not only help to destroy cancer cells but also remodel the tumour microenvironment by enhancing tumour-specific tropism of bone marrow-derived mesenchymal stromal cell (BM-MSC) from the peripheral circulation. However, the role of local MSCs and recruited BM-MSC under radiation were not well defined. Indeed, the functions of BM-MSC without irradiation intervention remained controversial in tumour progression: BM-MSC was previously shown to modulate the immune function of major immune cells, resulting in an impaired immunological sensitivity and to induce an increased risk of tumour recurrence. In contrast, it could also secrete various cytokines and possess anticancer effect.

METHODS

Three co-cultivation modules, 3D culture modules, and cancer organoids were established. The induction of cytokines secretion in hBM-MSCs after irradiation was analysed by ELISA array and flow cytometry. AutoMac separator was used to separate hBM-MSC and CRC automatically. Cells from the co-cultured group and the control group were then irradiated by UV-C lamp and X-ray. Proliferation assay and viability assay were performed.

RESULTS

In this study, we show that BM-MSCs can induce the EMT progression of CRC cells in vitro. When irradiated with low doses of ultraviolet radiation and X-rays, BM-MSCs show an anti-tumour effect by secreting certain cytokine (TNF-α, IFN-γ) that lead to the inhibition of proliferation and induction of apoptosis of CRC cells. This was further verified in a 3D culture model of a CRC cell in vitro. Furthermore, irradiation on the co-culture system induced the cleavage of caspase3, and attenuated the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/AKT and extracellular signal-regulated kinase in cancer cells. The signal pathways above might contribute to the cancer cell death.

CONCLUSIONS

Taken together, we show that BM-MSC can potentially promote the effect of radiotherapy in CRC.

Physical stimulation and scaffold composition efficiently support osteogenic differentiation of mesenchymal stem cells

BACKGROUND

Despite significant achievements in the field of tissue engineering, simplification and improvement of the existing protocols are of great importance. The use of complex differentiation media, due to the presence of multiple factors, may have some undesired effects on cell health and functions. Thus, minimizing the number of involved factors, while maintaining the differentiation efficiency, provides less costly and controllable conditions. Adipose-derived Mesenchymal stem cells (ASCs), the adult stem cells present in adipose tissue, can be a suitable source of stem cells due to abundant and ease of access. The aim of this study is to optimize the osteogenic differentiation of ASCs by chemical composition of scaffold, in the first step, and then by electromagnetic treatments.

METHODS

ASCs were cultured on PVA/PES scaffold and tissue culture polystyrene surfaces (TCPS) and osteogenic differentiation was performed with either osteogenic medium, or electromagnetic field or both. The impact of each treatment on ASCs growth and proliferation was measured by MTT assay. Changes in gene expression levels of osteogenic-specific markers including ALP and RUNX2 were determined by Real Time PCR. Furthermore, alkaline phosphatase activity and calcium deposition were measured.

RESULTS

The MTT assay showed the significant effects on cell growth and respiration in scaffold-seeded ASCs treated with electromagnetic field, compared to control TCPS plate. Also, the electromagnetic treatment, increased alkaline phosphatase activity and calcium deposition. Finally, Real Time PCR showed higher expression of ALP and RUNX2 genes in electromagnetic field groups compared to control groups.

CONCLUSION

It can be concluded that PVA/PES scaffold used in this study improved the osteogenic capacity of ASCs. Moreover, the osteogenic potential of ASCs seeded on PVA/PES scaffold could be augmented by electromagnetic field without any chemical stimulation.

Mesenchymal stem and progenitor cells of rats' bone marrow under chronic action of ionizing radiation

Under the influence of ionizing radiation on hematopoietic system, the level of its injury is determined not only by the radiosensitivity of hematopoietic stem cells, but also by radiation induced changes in microenvironment func tioning, in particular, mesenchymal stem cells as its components.

OBJECTIVE

to define functioning characteristics of mesenchymal stem and progenitor cells of rats' bone marrow under prolonged action of ionizing radiation as a result of 90Sr incorporation.

MATERIALS AND METHODS

We applied the model of Wistar rats' internal irradiation with 90Sr radionuclide and per formed the in vitro cultivation of their bone marrow mesenchymal cells. Colony forming efficiency in the in vitro cell culture was determined, as well as the possibility of these cells to form feeder layers and to support rat bone mar row hematopoietic cells in the culture of diffusion chambers in vitro.

RESULTS AND CONCLUSIONS

We established that chronic action of incorporated 90Sr radionuclide induced considerable decrease in proliferative activity of mesenchymal stem cells comparing to control, as well as the inhibition of the capability to prolonged support of hematopoietic processes in vitro by their feeder layers.Thus, bone marrow mesenchymal stem cells and their closest progeny - progenitor cells were characterized by rather high radiosensitivity under the influence of ionizing radiation, which was revealed in considerable decline of their functional activity in cell culture in vitro comparing to control indices as a result of irradiation.

Estrogen Regulates Bone Turnover by Targeting RANKL Expression in Bone Lining Cells

Estrogen is critical for skeletal homeostasis and regulates bone remodeling, in part, by modulating the expression of receptor activator of NF-κB ligand (RANKL), an essential cytokine for bone resorption by osteoclasts. RANKL can be produced by a variety of hematopoietic (e.g. T and B-cell) and mesenchymal (osteoblast lineage, chondrocyte) cell types. The cellular mechanisms by which estrogen acts on bone are still a matter of controversy. By using murine reconstitution models that allow for selective deletion of estrogen receptor-alpha (ERα) or selective inhibition of RANKL in hematopoietic vs. mesenchymal cells, in conjunction with in situ expression profiling in bone cells, we identified bone lining cells as important gatekeepers of estrogen-controlled bone resorption. Our data indicate that the increase in bone resorption observed in states of estrogen deficiency in mice is mainly caused by lack of ERα-mediated suppression of RANKL expression in bone lining cells.

Low level laser (LLL) attenuate LPS-induced inflammatory responses in mesenchymal stem cells via the suppression of NF-κB signaling pathway in vitro

Background

Considering promising results in animal models and patients, therapeutic use of MSCs for immune disease is likely to undergo continued evaluation. Low-lever laser (LLL) has been widely applied to retard the inflammatory reaction. LLL treatment can potentially be applied in anti-inflammatory therapy followed by stem cell therapy.

Aim of the study

The purpose of this study was to investigate the effect of LLL (660 nm) on the inflammatory reaction induced by LPS in human adipose derived mesenchymal stem cells (hADSCs) and pertinent mechanism.

Materials and methods

Anti-inflammatory activity of LLL was investigated by LPS-induced mesenchymal stem cells. The production and expression of pro-inflammatory cytokines were evaluated by ELISA kits and RT-qPCR. Nuclear translocation of NF-κB was indicated by immunofluorescent staining. Phosphorylation status of NF-κB p65 and IκBα were illustrated by western blot assay. ROS generation was measured with CM-H2DCFDA, and NO secretion was determined by DAF-FM. We studied surface expression of lymphocyte activation markers when Purified peripheral blood mononuclear cell (PBMC) were activated by phytohaemagglutinin (PHA) in the presence of 3 types of treated MSCs.

Results

LLL reduced the secretion of IL-1β, IL-6, IL8, ROS and NO in LPS treated MSCs. Immunofluorescent assay demonstrated the nuclear translocation decrease of NF-κB in LLL treated LPS induced MSCs. Western blot analysis also suggested that LLL suppressed NF-κB activation via regulating the phosphorylation of p65 and IκBα. MSC significantly reduced the expression of activation markers CD25 and CD69 on PHA-stimulated lymphocytes.

Conclusion

The results indicate that LLL suppressed the activation of NF-κB signaling pathway in LPS treated MSCs through inhibiting phosphorylation of p65 and IκBα, which results in good anti-inflammatory effect. In addition, LLL attenuated activation-associated markers CD25 and CD69 in co-cultures of PBMC and 3 types of treated MSCs.

Hypothermia reduces VEGF-165 expression, but not osteogenic differentiation of human adipose stem cells under hypoxia

Cryotherapy is successfully used in the clinic to reduce pain and inflammation after musculoskeletal damage, and might prevent secondary tissue damage under the prevalent hypoxic conditions. Whether cryotherapy reduces mesenchymal stem cell (MSC) number and differentiation under hypoxic conditions, causing impaired callus formation is unknown. We aimed to determine whether hypothermia modulates proliferation, apoptosis, nitric oxide production, VEGF gene and protein expression, and osteogenic/chondrogenic differentiation of human MSCs under hypoxia. Human adipose MSCs were cultured under hypoxia (37°C, 1% O2), hypothermia and hypoxia (30°C, 1% O2), or control conditions (37°C, 20% O2). Total DNA, protein, nitric oxide production, alkaline phosphatase activity, gene expression, and VEGF protein concentration were measured up to day 8. Hypoxia enhanced KI67 expression at day 4. The combination of hypothermia and hypoxia further enhanced KI67 gene expression compared to hypoxia alone, but was unable to prevent the 1.2-fold reduction in DNA amount caused by hypoxia at day 4. Addition of hypothermia to hypoxic cells did not alter the effect of hypoxia alone on BAX-to-BCL-2 ratio, alkaline phosphatase activity, gene expression of SOX9, COL1, or osteocalcin, or nitric oxide production. Hypothermia decreased the stimulating effect of hypoxia on VEGF-165 gene expression by 6-fold at day 4 and by 2-fold at day 8. Hypothermia also decreased VEGF protein expression under hypoxia by 2.9-fold at day 8. In conclusion, hypothermia decreased VEGF-165 gene and protein expression, but did not affect differentiation, or apoptosis of MSCs cultured under hypoxia. These in vitro results implicate that hypothermia treatment in vivo, applied to alleviate pain and inflammation, is not likely to harm early stages of callus formation.

Improved Human Bone Marrow Mesenchymal Stem Cell Osteogenesis in 3D Bioprinted Tissue Scaffolds with Low Intensity Pulsed Ultrasound Stimulation

3D printing and ultrasound techniques are showing great promise in the evolution of human musculoskeletal tissue repair and regeneration medicine. The uniqueness of the present study was to combine low intensity pulsed ultrasound (LIPUS) and advanced 3D printing techniques to synergistically improve growth and osteogenic differentiation of human mesenchymal stem cells (MSC). Specifically, polyethylene glycol diacrylate bioinks containing cell adhesive Arginine-Glycine-Aspartic acid-Serene (RGDS) peptide and/or nanocrystalline hydroxyapatite (nHA) were used to fabricate 3D scaffolds with different geometric patterns via novel table-top stereolithography 3D printer. The resultant scaffolds provide a highly porous and interconnected 3D environment to support cell proliferation. Scaffolds with small square pores were determined to be the optimal geometric pattern for MSC attachment and growth. The optimal LIPUS working parameters were determined to be 1.5 MHz, 20% duty cycle with 150 mW/cm(2) intensity. Results demonstrated that RGDS peptide and nHA containing 3D printed scaffolds under LIPUS treatment can greatly promote MSC proliferation, alkaline phosphatase activity, calcium deposition and total protein content. These results illustrate the effectiveness of the combination of LIPUS and biomimetic 3D printing scaffolds as a valuable combinatorial tool for improved MSC function, thus make them promising for future clinical and various regenerative medicine application.

Effect of low-level laser irradiation on proliferation of human dental mesenchymal stem cells; a systemic review

CONTEXT

Identification of factors that enhance the proliferation of human dental mesenchymal stem cells (DMSCs) is vital to facilitate tissue regeneration. The role of low-level laser irradiation (LLLI) on proliferation of human DMSCs has not been well established.

OBJECTIVE

To assess the effect of LLLI on proliferation of human DMSCs when applied in-vitro.

DATA SOURCES

Electronic search of literature was conducted (2000-2016) on PubMed, Web of Science, and Scopus databases. Search terms included low-level light therapy, low-level laser irradiation, low-level light irradiation, LLLT, humans, adolescent, adult, cells, cultured, periodontal ligament, dental pulp, stem cells, dental pulp stem cells, mesenchymal stem cells, periodontal ligament stem cell, deciduous teeth, cell proliferation, adult stem cells, radiation, and proliferation.

RESULTS

The literature search identified 165 studies with 6 being eligible for inclusion; all used diode lasers; 5 studies used InGaAIP diode lasers; 4 used 660nm, and the other two applied 810nm or 980nm wavelength LLLI. The distance between the DMSCs and the laser spot ranged between 0.5mm to 2mm. The time intervals of cell proliferation analysis ranged from 0h to 7days after LLLI. After 660nm LLLI, an increase in the DMSC's proliferation was reported [DMSCs extracted from dental pulp of deciduous teeth (two irradiations, 3J/cm(2), 20mW was more effective than 40mW), adult teeth (two irradiations, 0.5 and 1.0J/cm(2), 30mW), and from adult periodontal ligament (two irradiations, 1.0J/cm(2) was more effective than 0.5J/cm(2), 30mW)]. Similarly, an increase in the proliferation of DMSCs extracted from dental pulp of adult teeth was reported after 810nm LLLI (7 irradiations in 7days, 0.1 and 0.2J/cm(2), 60mW) or 980nm LLLI (single irradiation, 3J/cm(2), 100mW). However, 660nm LLLI in one study did not increase the proliferation of DMSCs (single irradiation, energy densities of 0.05, 0.30, 7, and 42J/cm(2), 28mW).

CONCLUSION

There is limited evidence that in-vitro LLLI (660/810/980nm, with energy densities of 0.1-3J/cm(2)) increases the proliferation of DMSCs. Considering the limited evidence and their method heterogeneity it is difficult to reach a firm conclusion. Further research is necessary to identify the optimal characteristics of the LLLI setting (wave length, energy density, power output, frequency/duration of irradiations, distance between the cells and the laser spot/probe) to increase proliferation of DMSCs, and assess its impact on replicative senescence, as well as determine feasibility of the use in the clinical setting.

[Effects of pulsed ultrasound and pulsed electromagnetic field on the extracellular matrix secretion of rat bone marrow mesenchymal stem cell pellets in chondrogenesis]

OBJECTIVE

To study the effects of pulsed ultrasound (PUS) and pulsed electromagnetic fields (PEMF) on the secretion of extracellular matrix from a culture complex during in vitro chondrogenesis.

METHODS

All the rat bone marrow mesen- chymal stem cell pellets were cultured in achondrogenic medium. Different intensities of PUS (100, 150, and 200 mW · cm⁻²) and PEMF (1, 2, and 5 mT) were applied to the cell pellets for 2 weeks. Group N was cultured without PUS and PEMF stimu- lation as control. The culture medium was collected after 2 weeks of culture. Enzyme-linked immunosorbent assay (ELISA) was used to detect the type of collagen and glycosaminoglycan (GAG) in the culture medium.

RESULTS

PUS increased the secreting-type collagen and GAG from cell pellets compared with group N (P < 0.05), whereas there was no difference in different intensities (P > 0.05). PEMF had no significant effect on the secretion of the type of collagen (P > 0.05). A PEMF of 1 mT had no significant effect on the secretion of GAG (P > 0.05). A PEMF 2 and 5 mT decreased the secretion of GAG (P < 0.05).

CONCLUSION

To prevent the secretary of extracellular matrix may play a role in chondrogenic effect of PEMF.

[Therapeutic Effects of Multipotent Mesenchymal Stromal Cells after Irradiation]

Multipotent mesenchymal stromal cells (MSC) are now considered to be a perspective multifunctional treatment option for radiation side effects. At present.a great number of sufficient evidence has been collected in favor of therapeutic effects of MSCs in acute radiation reactions. It has been shown that MSC-based products injected locally or systemically have therapeutic effects on irradiated organs and tissues. This review presents summarized experimental and clinical data about protective and regenerative effects of MSCs on different radiation-injured organs and tissues; the main probable therapeutic mechanisms of their action are also discussed.

Effects of Focused Extracorporeal Shock Waves on Bone Marrow Mesenchymal Stem Cells in Patients with Avascular Necrosis of the Femoral Head

To observe the effect of extracorporeal shock waves (ESWs) on bone marrow mesenchymal stem cells (MSCs) in patients with avascular necrosis of the femoral head, we collected bone marrow donated by patients and then cultivated and passaged MSCs in vitro using density gradient centrifugation combined with adherence screening methods. The P3 generation MSCs were divided into the ESW group and the control group. The cell counting kit for MSCs detected some proliferation differences. Cytochemistry, alkaline phosphatase staining and Alizarin red staining were used to determine alkaline phosphatase content. Simultaneously, real-time polymerase factor α1, osteocalcin and peroxisome proliferator-activated receptor γ. Together, the results of our study first indicate that moderate ESW intensity, which is instrumental in enhancing MSC proliferation, inducing conversion of MSCs into osteoblasts, and inhibiting differentiation of MSCs into adipocytes from MSCs, is one of the effective mechanisms for treating avascular necrosis of the femoral head.

Focal Adhesion Kinase Signaling Mediated the Enhancement of Osteogenesis of Human Mesenchymal Stem Cells Induced by Extracorporeal Shockwave

Extracorporeal shockwave (ESW) has been shown of great potential in promoting the osteogenesis of bone marrow mesenchymal stem cells (BMSCs), but it is unknown whether this osteogenic promotion effect can also be achieved in other MSCs (i.e., tendon-derived stem cells (TDSCs) and adipose-derived stem cells (ADSCs)). In the current study, we aimed not only to compare the osteogenic effects of BMSCs induced by ESW to those of TDSCs and ADSCs; but also to investigate the underlying mechanisms. We show here that ESW (0.16 mj/mm(2)) significantly promoted the osteogenic differentiation in all the tested types of MSCs, accompanied with the downregulation of miR-138, but the activation of FAK, ERK1/2, and RUNX2. The enhancement of osteogenesis in these MSCs was consistently abolished when the cells were pretreated with one of the following conditions: overexpression of miR-138, FAK knockdown using specific siRNA, and U0126, implying that all of these elements are indispensable for mediating the effect of ESW. Moreover, our study provides converging genetic and molecular evidence that the miR-138-FAK-ERK1/2-RUNX2 machinery can be generally activated in ESW-preconditioned MSCs, suggesting that ESW may be a promising therapeutic strategy for the enhancement of osteogenesis of MSCs, regardless of their origins.