The cannabinoid receptor type 1 is essential for mesenchymal stem cell survival and differentiation: implications for bone health

Effects of cannabinoid receptor activation on Porphyromonas gingivalis lipopolysaccharide stimulation in human periodontal ligament stem cells in vitro

PURPOSE

Periodontitis is an inflammatory disease that results in the loss of periodontal tissue. The endocannabinoid system has anti-inflammatory properties and displays considerable potential for tissue regeneration. In this study, we aimed to explore whether the activation of this system can alleviate or reverse the inflammatory phenotype of human periodontal ligament stem cells (hPDLSCs) induced by exposure to the inflammagen lipopolysaccharide (LPS).

METHODS

We investigated the effects of activating specific cannabinoid receptors (CB1 and CB2) on the inflammatory phenotype of LPS-stimulated hPDLSCs. The exogenous ligands WIN55,212-2 and JWH-133 were employed to target the cannabinoid receptors. We conducted a thorough assessment of cell proliferation, metabolic activity, and adipogenic, osteogenic, and chondrogenic differentiation potential. Additionally, we measured cytokine release using enzyme-linked immunosorbent assays.

RESULTS

Exposure to Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) caused an increase in cell proliferation while decreasing metabolic activity. While this exposure did not influence adipogenic or chondrogenic differentiation, it did result in reduced osteogenesis. Additionally, LPS induced the release of interleukin (IL)-6, IL-8, and monocyte chemoattractant protein 1. Immunolabeling revealed the presence of CB1 and CB2 on the cellular membrane, with these receptors playing distinct roles in hPDLSCs. The CB1 agonist WIN55,212-2 was found to increase metabolic activity and promote adipogenic differentiation, whereas the CB2 agonist JWH-133 promoted cell proliferation and osteogenic differentiation. When hPDLSCs were co-exposed to Pg-LPS and CB ligands, JWH-133 slightly ameliorated the inhibition of osteogenic differentiation and suppressed the release of inflammatory cytokines.

CONCLUSIONS

This study clarifies the effects of specific CB receptor activation on hPDLCs and the inflammatory phenotype. Stimulation of the endocannabinoid system through the manipulation of endogenous or the application of exogenous cannabinoids in vivo may represent a potent therapeutic option for combating periodontal inflammatory disorders.

Association between history of cannabis use and outcomes after total hip or knee arthroplasty: a systematic review and meta-analysis

Background

Cannabis use may be increasing as countries legalize it and it becomes socially acceptable. A history of cannabis use may increase risk of complications after various kinds of surgery and compromise functional recovery. Here we systematically reviewed and meta-analyzed available evidence on how history of cannabis use affects recovery after hip or knee arthroplasty (THA/TKA).

Methods

The PubMed, EMBASE, and Web of Science databases were comprehensively searched and studies were selected and analyzed in accordance with the PRISMA guidelines. The methodological quality of included studies was assessed based on the Newcastle-Ottawa Scale, while quality of evidence was evaluated according to the "Grading of recommendations assessment, development, and evaluation" system. Data on various outcomes were pooled when appropriate and meta-analyzed.

Results

The systematic review included 16 cohort studies involving 5.91 million patients. Meta-analysis linked history of cannabis use to higher risk of the following outcomes: revision (RR 1.68, 95% CI 1.31-2.16), mechanical loosening (RR 1.77, 95% CI 1.52-2.07), periprosthetic fracture (RR 1.85, 95% CI 1.38-2.48), dislocation (RR 2.10, 95% CI 1.18-3.73), cardiovascular events (RR 2.49, 95% CI 1.22-5.08), cerebrovascular events (RR 3.15, 95% CI 2.54-3.91), pneumonia (RR 3.97, 95% CI 3.49-4.51), respiratory failure (RR 4.10, 95% CI 3.38-4.97), urinary tract infection (RR 2.46, 95% CI 1.84-3.28), acute kidney injury (RR 3.25, 95% CI 2.94-3.60), venous thromboembolism (RR 1.48, 95% CI 1.34-1.63), and deep vein thrombosis (RR 1.42, 95% CI 1.19-1.70). In addition, cannabis use was associated with significantly greater risk of postoperative transfusion (RR 2.23, 95% CI 1.83-2.71) as well as higher hospitalization costs.

Conclusion

History of cannabis use significantly increases the risk of numerous complications and transfusion after THA or TKA, leading to greater healthcare costs. Clinicians should consider these factors when treating cannabis users, and pre-surgical protocols should give special consideration to patients with history of cannbis use.

Cannabis Use is Associated With Higher Rates of Pseudarthrosis Following TLIF: A Multi-Institutional Matched-Cohort Study

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

To compare the rates of pseudarthrosis in patients undergoing 1 to 3 level transforaminal lumbar interbody fusion (TLIF) procedures between cannabis users and noncannabis users.

SUMMARY OF BACKGROUND DATA

Recreational use of cannabis is common, though it remains poorly studied and legally ambiguous in the United States. Patients with back pain may turn to adjunctive use of cannabis to manage their pain. However, the implications of cannabis use on the achievement of bony fusion are not well-characterized.

METHODS

Patients who underwent 1 to 3 level TLIF for degenerative disc disease or degenerative spondylolisthesis between 2010 and 2022 were identified using the PearlDiver Mariner all-claims insurance database. Cannabis users were identified with ICD 10 code F12.90. Patients undergoing surgery for nondegenerative pathologies such as tumors, trauma, or infection were excluded. 1:1 exact matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with pseudarthrosis in a linear regression model. The primary outcome measure was development of pseudarthrosis within 24 months after 1 to 3 level TLIF. The secondary outcomes were the development of all-cause surgical complications as well as all-cause medical complications.

RESULTS

A 1:1 exact matching resulted in two equal groups of 1593 patients who did or did not use cannabis and underwent 1 to 3 level TLIF. Patients who used cannabis were 80% more likely to experience pseudarthrosis compared with patients who do not [relative risk (RR): 1.816, 95% CI: 1.291-2.556, P <0.001]. Similarly, cannabis use was associated with significantly higher rates of all-cause surgical complications (RR: 2.350, 95% CI: 1.399-3.947, P =0.001) and all-cause medical complications (RR: 1.934, 95% CI: 1.516-2.467, P <0.001).

CONCLUSION

After 1:1 exact matching to control for confounding variables, the findings of this study suggest that cannabis use is associated with higher rates of pseudarthrosis, as well as higher rates of all-cause surgical and all-cause medical complications. Further studies are needed to corroborate our findings.

Tumor necrosis factor α, and agonist and antagonists of cannabinoid receptor type 1 and type 2 alter the immunophenotype of stem cells from human exfoliated deciduous teeth

OBJECTIVE

To verify the involvement of the endocannabinoid system in the immunomodulatory profile of stem cells from human exfoliated deciduous teeth, in the presence or absence of TNF-α, and agonist and antagonists of CB1 and CB2.

METHODS

Stem cells from human exfoliated deciduous teeth were cultured in the presence or absence of an agonist, anandamide, and two antagonists, AM251 and SR144528, of CB1 and CB2 receptors, with or without TNF-α stimulation. For analysis of immunomodulation, surface molecules linked to immunomodulation, namely human leukocyte antigen-DR isotype (HLA-DR), and programmed death ligands 1 (PD-L1) and 2 (PD-L2) were measured using flow cytometry.

RESULTS

The inhibition of endocannabinoid receptors together with the proinflammatory effect of TNF-α resulted in increased HLA-DR expression in stem cells from human exfoliated deciduous teeth, as well as, in these cells acquiring an anti-inflammatory profile by enhancing the expression of PD-L1 and PD-L2.

CONCLUSION

Stem cells from human exfoliated deciduous teeth respond to the endocannabinoid system and TNF-α by altering key immune response molecules. Inhibition of endocannabinoid receptors and TNF-α led to an increase in HLA-DR, PD-L1, and PD-L2 levels in stem cells from human exfoliated deciduous teeth. This study shows the interaction between mesenchymal stromal cells and the immune and endocannabinoid systems.

Cannabis Use in Patients With Distal Radius Fractures: A Moment of Unity?

BACKGROUND

As legalization of cannabis spreads, an increasing number of patients who use cannabis are being seen in the clinical setting. This study examined the impact of cannabis and tobacco use on postoperative complications following open reduction and internal fixation (ORIF) of distal radius fractures.

METHODS

A national, all-payer database was queried to identify patients who underwent ORIF of a distal radius fracture between 2015 and 2020 (n = 970 747). Patients were stratified into the following groups: (1) tobacco use (n = 86 941), (2) cannabis use (n = 898), (3) tobacco and cannabis use (n = 9842), and (4) neither tobacco nor cannabis use ("control", 747 892). Multivariable logistic regression was used to identify risk factors for infection, nonunion, and malunion within the first postoperative year.

RESULTS

Concomitant use of tobacco and cannabis was associated with a higher rate of nonunion (5.0%) compared to tobacco or cannabis use alone (P < .001). Multivariate analysis identified cannabis-only use (odds ratio [OR] 1.25), tobacco-only use (OR 2.17), and concurrent tobacco and cannabis use (OR 1.78) as risk factors for infection within the first postoperative year. Similarly, cannabis-only use (OR 1.47), tobacco-only use (OR 1.92), and concurrent tobacco and cannabis use (OR 2.52) were associated with an increased risk of malunion.

CONCLUSIONS

Cannabis use is associated with an elevated risk of infection and malunion following operative management of a distal radius fracture. Concomitant use of cannabis and tobacco poses an elevated risk of nonunion and malunion compared to tobacco use alone.

KDM4D enhances osteo/dentinogenic differentiation and migration of SCAPs via binding to RPS5

OBJECTIVES

Stem cells of the apical papilla (SCAPs) provide promising candidates for dental pulp regeneration. Despite great advances in the transcriptional controls of the SCAPs fate, little is known about the regulation of SCAP differentiation.

MATERIALS AND METHODS

Short hairpin RNAs and full-length RNA were used to deplete or overexpress lysine demethylase 4D (KDM4D) gene expression. Western blotting, real-time RT-PCR, alizarin red staining, and scratch migration assays were used to study the role of KDM4D and the ribosomal protein encoded by RPS5 in SCAPs. RNA microarray, chromatin Immunoprecipitation (ChIP), and co-immunoprecipitation (Co-IP) assays were performed to explore the underlying molecular mechanisms.

RESULTS

KDM4D enhanced the osteo/dentinogenic differentiation, migration, and chemotaxis of SCAPs. The microarray results revealed that 88 mRNAs were differentially expressed in KDM4D-overexpressed SCAPs. ChIP results showed knock-down of KDM4D increased the level of H3K9me2 and H3K9me3 in CNR1 promoter region. There were 37 possible binding partners of KDM4D. KDM4D was found to combine with RPS5, which also promoted the osteo/dentinogenic differentiation, migration, and chemotaxis of SCAPs.

CONCLUSIONS

KDM4D promoted the osteo/dentinogenic differentiation and migration potential of SCAPs in combination with RPS5, which provides a therapeutic clue for improving SCAPs-based dental tissue regeneration.

Cannabidiol for musculoskeletal regenerative medicine

Chronic musculoskeletal (MSK) pain is one of the most prevalent causes, which lead patients to a physician's office. The most common disorders affecting MSK structures are osteoarthritis, rheumatoid arthritis, back pain, and myofascial pain syndrome, which are all responsible for major pain and physical disability. Although there are many known management strategies currently in practice, phytotherapeutic compounds have recently begun to rise in the medical community, especially cannabidiol (CBD). This natural, non-intoxicating molecule derived from the cannabis plant has shown interesting results in many preclinical studies and some clinical settings. CBD plays vital roles in human health that go well beyond the classic immunomodulatory, anti-inflammatory, and antinociceptive properties. Recent studies demonstrated that CBD also improves cell proliferation and migration, especially in mesenchymal stem cells (MSCs). The foremost objective of this review article is to discuss the therapeutic potential of CBD in the context of MSK regenerative medicine. Numerous studies listed in the literature indicate that CBD possesses a significant capacity to modulate mammalian tissue to attenuate and reverse the notorious hallmarks of chronic musculoskeletal disorders (MSDs). The most of the research included in this review report common findings like immunomodulation and stimulation of cell activity associated with tissue regeneration, especially in human MSCs. CBD is considered safe and well tolerated as no serious adverse effects were reported. CBD promotes many positive effects which can manage detrimental alterations brought on by chronic MSDs. Since the application of CBD for MSK health is still undergoing expansion, additional randomized clinical trials are warranted to further clarify its efficacy and to understand its cellular mechanisms.

Tetrahydrocannabivarin (THCV) Protects Adipose-Derived Mesenchymal Stem Cells (ASC) against Endoplasmic Reticulum Stress Development and Reduces Inflammation during Adipogenesis

The endoplasmic reticulum (ER) fulfills essential duties in cell physiology, and impairment of this organelle's functions is associated with a wide number of metabolic diseases. When ER stress is generated in the adipose tissue, it is observed that the metabolism and energy homeostasis of the adipocytes are altered, leading to obesity-associated metabolic disorders such as type 2 diabetes (T2D). In the present work, we aimed to evaluate the protective effects of Δ9-tetrahydrocannabivarin (THCV, a cannabinoid compound isolated from Cannabis sativa L.) against ER stress in adipose-derived mesenchymal stem cells. Our results show that pre-treatment with THCV prevents the subcellular alteration of cell components such as nuclei, F-actin, or mitochondria distribution, and restores cell migration, cell proliferation and colony-forming capacity upon ER stress. In addition, THCV partially reverts the effects that ER stress induces regarding the activation of apoptosis and the altered anti- and pro-inflammatory cytokine profile. This indicates the protective characteristics of this cannabinoid compound in the adipose tissue. Most importantly, our data demonstrate that THCV decreases the expression of genes involved in the unfolded protein response (UPR) pathway, which were upregulated upon induction of ER stress. Altogether, our study shows that the cannabinoid THCV is a promising compound that counters the harmful effects triggered by ER stress in the adipose tissue. This work paves the way for the development of new therapeutic means based on THCV and its regenerative properties to create a favorable environment for the development of healthy mature adipocyte tissue and to reduce the incidence and clinical outcome of metabolic diseases such as diabetes.

Examining the role of cannabinoids on osteoporosis: a review

PURPOSE

Prior research studies have shown that the endocannabinoid system, influenced by CBD and THC, plays a role in bone remodeling. As both the research on cannabis and use of cannabis continue to grow, novel medicinal uses of both its constituents as well as the whole plant are being discovered. This review examines the role of cannabinoids on osteoporosis, more specifically, the endocannabinoid system and its role in bone remodeling and the involvement of the cannabinoid receptors 1 and 2 in bone health, as well as the effects of Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and synthetic cannabinoids on bone.

METHODS

A comprehensive literature search of online databases including PUBMED was utilized.

RESULTS

A total of 29 studies investigating the effects of cannabis and/or its constituents as well as the activation or inactivation of cannabinoid receptors 1 and 2 were included and discussed.

CONCLUSION

While many of the mechanisms are still not yet fully understood, both preclinical and clinical studies show that the effects of cannabis mediated through the endocannabinoid system may prove to be an effective treatment option for individuals with osteoporosis.

Cannabidiol (CBD) Protects Adipose-Derived Mesenchymal Stem Cells (ASCs) against Endoplasmic Reticulum Stress Development and Its Complications

BACKGROUND

Recent studies suggested that individuals with metabolic disorders have altered function of adipocytes and adipose stem cell subpopulations, which impairs tissue homeostasis, promoting insulin resistance and diabetes development. The non-psychoactive phytocannabinoid CBD was found to modulate adipose tissue metabolism, however, its exact role in controlling ASCs' fate is still poorly understood.

OBJECTIVES

This investigation aimed to elucidate whether pretreatment of ASCs with CBD can protect against ER stress development and maintain the cytophysiological properties of cells.

METHODS

Human ASCs were cultured under control and adipogenic conditions. Prior to the experiments, cells in the experimental group were pretreated with CBD following the addition of an ER stress inducer-tunicamycin. After the experiments, the cells were subsequently tested for expression of the apoptotic, ER stress, and anti-inflammatory-related genes using RT-qPCR. Oxidative stress was analysed with flow cytometric assays.

RESULTS

Cells pretreated with CBD displayed decreased apoptosis and enhanced proliferation rate. Additionally, the expression of pro-inflammatory cytokines and miRNAs was significantly reduced. The obtained results also demonstrated an obvious reduction in intracellular accumulated ROS and NO, as well as mitigated ER stress through the down-regulation of IRE-1, PERK, CHOP, and ATF6 transcripts upon CBD treatment.

CONCLUSION

The presented data provide the evidence that CBD protects ASCs against ER stress development and its complications and, thus, offers new insights for the management of obesity through the regulation of adipose tissue dynamics.

Effect and Related Mechanism of Platelet-Rich Plasma on the Osteogenic Differentiation of Human Adipose-Derived Stem Cells

Objective

Human adipose-derived stem cells (hADSCs) are ideal seed cells for the regeneration of alveolar bone defects. Platelet-rich plasma (PRP), which is rich in growth factors, promotes tissue repair. The purpose of the present study was to investigate whether PRP promotes the osteogenic differentiation of hADSCs and to perform high-throughput sequencing to explore the possible mechanism.

Methods

hADSCs were divided into the three following groups: CON group, OM group, and PRP group. Osteogenesis was detected by Alizarin Red staining on day 14. Total RNA was extracted from the OM and PRP groups for high-throughput sequencing. The target genes of the differentially expressed osteogenic-related miRNAs were predicted, and combined miRNA/mRNA analysis was then performed. The mRNA and protein expression levels of hsa-miR-212-5p, type 1 cannabinoid receptor (CNR1), alkaline phosphatase (ALP), Runx2, osteocalcin (OCN), and collagen 1 A1 (COL1A1) in the OM and PRP groups were detected by qRT–PCR and Western blot analyses. The binding between hsa-miR-212-5p and CNR1 was detected by a dual-luciferase reporter assay.

Results

Both the OM and PRP groups exhibited enhanced proliferation of hADSCs, and the differences at 48 h and 72 h were statistically significant (P < 0.05). The PRP group had significantly more calcium nodules than the CON group (P < 0.05). Through high-throughput sequencing analysis, differential miRNA and mRNA expression profiles were obtained. During hADSC osteogenesis, the expression of hsa-miR-212-5p was downregulated, and the expression of CNR1 was upregulated. hsa-miR-212-5p was found to bind directly to the 3′ UTR of CNR1.

Conclusions

The present findings indicated that downregulation of hsa-miR-212-5p and upregulation of CNR1 may be involved in the process by which PRP promotes the osteogenic differentiation of hADSCs.

Activation of cannabinoid receptors in breast cancer cells improves osteoblast viability in cancer-bone interaction model while reducing breast cancer cell survival and migration

The endocannabinoid system has been postulated to help restrict cancer progression and maintain osteoblastic function during bone metastasis. Herein, the effects of cannabinoid receptor (CB) type 1 and 2 activation on breast cancer cell and osteoblast interaction were investigated by using ACEA and GW405833 as CB1 and CB2 agonists, respectively. Our results showed that breast cancer cell (MDA-MB-231)-derived conditioned media markedly decreased osteoblast-like UMR-106 cell viability. In contrast, media from MDA-MB-231 cells pre-treated with GW405833 improved UMR-106 cell viability. MDA-MB-231 cells were apparently more susceptible to both CB agonists than UMR-106 cells. Thereafter, we sought to answer the question as to how CB agonists reduced MDA-MB-231 cell virulence. Present data showed that co-activation of CB1 and CB2 exerted cytotoxic effects on MDA-MB-231 cells by increasing apoptotic cell death through suppression of the NF-κB signaling pathway in an ROS-independent mechanism. ACEA or GW405833 alone or in combination also inhibited MDA-MB-231 cell migration. Thus, it can be concluded that the endocannabinoid system is able to provide protection during breast cancer bone metastasis by interfering cancer and bone cell interaction as well as by the direct suppression of cancer cell growth and migration.

Analyzing the Impact of Cannabinoids on the Treatment of Spinal Disorders

PURPOSE OF REVIEW

Cannabis is among the most used illicit substances globally, with medical applications, increased legalization, and shifting social attitudes leading to increased use in recent years. Cannabinoids are a group of psychoactive substances found within the cannabis plant, with the most common being Δ9-tetrahydrocannabinol and cannabidiol. Due to the high prevalence of use, it is increasingly important to evaluate the effects of cannabis and cannabinoids on spine patients, in both operative and nonoperative settings.

RECENT FINDINGS

Cannabis and cannabinoids may be effective in treating patients with chronic conditions such as back pain and spinal cord injuries. Longitudinal effects and implications on surgical outcomes and complications are poorly understood. High-quality, outcomes-focused research can inform approaches for clinicians to approach cannabis and cannabinoid use. Studies to elucidate the standardization of cannabis regimens can help develop guidelines for potential therapeutic applications. Cannabis and cannabinoids may be useful alternatives or additions for many spine patients, but future research is needed for recommendations to be determined. Our manuscript reviews the available literature regarding cannabis use and various spinal conditions, organizing our findings into the following narrative themes: (1) the management of chronic lower back pain, (2) perioperative outcomes, (3) cannabis use in general orthopaedic procedures, and (4) spinal cord injuries.

Marijuana Use Results in Increased Time to Union in Surgically Treated Pediatric Fracture Patients

OBJECTIVE

To identify the impact of marijuana use on fracture healing in surgically treated pediatric patients.

DESIGN

Retrospective review.

SETTING

Level 1 trauma center, single-center study.

PATIENTS/PARTICIPANTS

Surgically treated pediatric patients 10-18 years with extremity fractures from 2010 to 2020. Conservatively treated patients and patients with nonunions were excluded from the study. Three hundred thirty-nine patients were included in the study, 21 of which were confirmed marijuana users by toxicology screening.

INTERVENTION

Surgical treatment of extremity fractures by any type of fixation.

MAIN OUTCOME MEASUREMENTS

Time to union was the primary outcome and was defined as radiographic evidence of bridging callus on all sides of the fracture and absence of the previous fracture line. Analysis of covariance, logistic regression analysis, and Fisher exact tests were used to establish the relationship between all collected variables and time to radiographic union.

RESULTS

The average time to union for marijuana users (159.1 ± 69.5 days, 95% confidence interval) was significantly longer than for nonusers (80.3 ± 7.8 days), P < 0.001. The odds of having a time to union of greater than 4 months and greater than 6 months were 4.17 (P = 0.00192) and 6.19 (P = 0.000159), respectively, for marijuana users compared with nonusers.

CONCLUSION

Marijuana users demonstrated longer time to union in surgically treated pediatric fracture patients.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Marijuana in Orthopaedics: Effects on Bone Health, Wound-Healing, Surgical Complications, and Pain Management

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Marijuana use is on the rise in the United States, and there is a paucity of information on the effects of cannabis and its chemical constituents on bone health, wound-healing, surgical complications, and pain management.

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Current evidence suggests that cannabidiol (CBD) may enhance bone health and metabolism, while Δ9-tetrahydrocannabinol (Δ9-THC), the major psychoactive component in marijuana, has an inhibitory effect.

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Marijuana users are at higher risk for delayed bone-healing, demonstrate lower bone mineral density, are at increased risk for fracture, and may experience postoperative complications such as increased opioid use and hyperemesis.

The cannabinoid receptor I (CB1) enhanced the osteogenic differentiation of BMSCs by rescue impaired mitochondrial metabolism function under inflammatory condition

Background

Periodontitis is a chronic infectious disease leading to bone resorption and periodontal tissue disruption under inflammatory stimulation. The osteogenic differentiation ability of mesenchymal stem cells (MSCs) is impaired under the inflammatory environment, which limits the effect of treatment. The cannabinoid receptor I (CB1) is the main effector of the endogenous cannabinoid system (ECS), and our previous study verified that CB1 could enhance the osteo/dentinogenic differentiation of dental MSCs, which might be a target for alveolar bone regeneration. However, the effect of CB1 on the osteogenic differentiation of MSCs derived from bone remains unknown. In present study, we investigated the role and mechanism of CB1 on mitochondrial function and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) under inflammatory environment.

Methods

Alkaline phosphatase (ALP) activity, alizarin red staining, quantitative calcium analysis, and osteogenic markers were used to detect the osteogenic differentiation ability of BMSCs. Real-time RT-PCR and Western blot were used to detect the gene expression. Seahorse Cell Mito Stress Test was used to detect the oxygen consumption rate (OCR). JC-10 assay was used to determine the mitochondrial membrane potential (MMP).

Results

CB1 increased osteogenic differentiation potential and mitochondrial energy metabolism, including the OCR, MMP, and enhanced the expressions of Nrf1 and Nrf2 in hBMSCs without or with TNF-α or INF-γ stimulation. Then, the inhibitor of mitochondrial electron transport chain (ETC), rotenone (ROT), inhibited the osteogenic differentiation in hBMSCs, and CB1 could rescue ROT impaired osteogenic differentiation potentials of hBMSCs without or with TNF-α or INF-γ stimulation. Activation of ETC by Coenzyme Q10 (CoQ10) could restore the impaired osteogenic differentiation of hBMSCs by depletion of CB1 without or with TNF-α or INF-γ stimulation. Mechanismly, CB1 could activate the JNK signaling pathway, p38 MAPK signaling pathway, and inhibit the Erk1/2 signaling pathway.

Conclusions

The activating of CB1 enhanced the osteogenic differentiation by rescuing the mitochondrial metabolism function in hBMSCs under the inflammatory environment, suggesting that CB1 is a potential target for enhancing bone regeneration under the inflammatory environment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02702-9.

Dronabinol inhibits alveolar bone remodeling in tooth movement of rats

INTRODUCTION

Orthodontic tooth movement is reliant on the process of bone remodeling, and a variety of medications impact the ability of teeth to move through bone. Marijuana is the most widely used recreational drug in the world, and early studies suggest the drug impacts bone remodeling as tetrahydrocannabinol binds to cannabinoid receptors which play a role in bone homeostasis. This study aimed to assess the impact of dronabinol on alveolar bone remodeling in rats with otherwise healthy tissue when subjected to orthodontic forces.

METHODS

Thirty male Sprague Dawley rats were equally allocated into 2 groups. Orthodontic appliances were placed in all animals, which consisted of a nickel-titanium coil ligated from the maxillary first molar to the central incisor. The appliance was activated to deliver a force to move teeth together. Over 21 days, daily injections of either dronabinol or the control (solvent) were given to the rats. Cephalometric analysis, histology, and bone remodeling profiles of both groups were analyzed and compared.

RESULTS

Teeth moved in both the dronabinol and control groups (P <0.05). Tooth movement in the control group followed the typical process of orthodontic tooth movement: periodontal width narrowing and bone resorption on the compression side of the tooth, with an overall decrease in the height of the alveolar bone. In contrast, the dronabinol group showed an abnormal response to tooth movement: no bone resorption on the compression side of the tooth, increased bone formation on the tension side, and the maintenance of the height of the alveolar crest. In the dronabinol group, there were also significantly more osteoclasts and osteoblasts in the alveolar bone than in the control group.

CONCLUSIONS

These results demonstrate that dronabinol attenuates orthodontic tooth movement by decreasing bone resorption, which could have implications for other bone-related recovery processes.

Effects of Marijuana Use in Patients with Orthopaedic Trauma

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The use of cannabis and cannabis-related products has increased dramatically in the last 2 decades. As states continue to legalize cannabis products, it is important for surgeons to understand the effects they may have on patients who have sustained orthopaedic trauma.

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Cannabinoids have been shown to decrease the severity of certain symptoms related to traumatic brain injury as well as posttraumatic stress disorder.

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Cannabinoids can modulate the body's endocannabinoid system, which can play an important role in bone homeostasis. Activation of cannabinoid receptors has been shown to be bone-protective in adults.

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Venous thromboembolism is a major concern for trauma patients. Cannabis use has been linked to overall increased rates of venous thromboembolism events.

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Literature regarding human-based cannabis studies is sparse; however, the growing field is opening new opportunities for research of this topic.

Endocannabinoids Regulate Stem Cells of the Apical Papilla via a Cannabinoid Receptor and TRPV1-Independent Mechanism

INTRODUCTION

Endogenous cannabinoids (endocannabinoids [eCBs]) have been shown to have a multitude of functions including neurotransmission and immune modulatory effects. This study aimed to evaluate if stem cells of the apical papilla (SCAP) express the receptors and enzymes of the endocannabinoid system (ECS) and whether eCBs regulate their proliferation and mineralization potential.

METHODS

Gene expression of the main components of the ECS and transient receptor potential vanilloid 1 (TRPV1) was evaluated in SCAP cultures. SCAP were treated with 2 concentrations of eCBs and/or capsazepine, a TRPV1 antagonist. SCAP viability was evaluated after 1, 4, and 7 days. Osteogenic differentiation was assessed after 14 days, and the gene expression of mineralization markers was assessed after 7 days.

RESULTS

The enzymes of ECS and TRPV1 but not the cannabinoid receptors (cannabinoid receptors 1 and 2) were expressed in SCAP. Anandamide, 2-arachidonoylglycerol, and N-arachidonoylphenolamine (AM-404) reduced SCAP viability in all experimental periods at the highest concentration compared with the group with no treatment. Anandamide and AM-404 did not inhibit SCAP differentiation potential, but 2-arachidonoylglycerol at the highest concentration did. SCAP treated with AM-404 presented a down-regulation in gene expression of alkaline phosphatase (ALP), dentin matrix protein 1 (DMP-1), and dentin sialophosphoprotein (DSPP) compared with the proliferation medium group but not with control group.

CONCLUSIONS

SCAP expressed the genes of the main components of ECS and TRPV1, and eCBs can affect SCAP viability, mineralization, and gene expression.

Endocannabinoid system: Role in blood cell development, neuroimmune interactions and associated disorders

The endocannabinoid system (ECS) is a complex physiological network involved in creating homeostasis and maintaining human health. Studies of the last 40 years have shown that endocannabinoids (ECs), a group of bioactive lipids, together with their set of receptors, function as one of the most important physiologic systems in human body. ECs and cannabinoid receptors (CBRs) are found throughout the body: in the brain tissues, immune cells, and in the peripheral organs and tissues as well. In recent years, ECs have emerged as key modulators of affect, neurotransmitter release, immune function, and several other physiological functions. This modulatory homoeostatic system operates in the regulation of brain activity and states of physical health and disease. In several research studies and patents the ECS has been recognised with neuro-protective properties thus it might be a target in neurodegenerative diseases. Most immune cells express these bioactive lipids and their receptors, recent data also highlight the immunomodulatory effects of endocannabinoids. Interplay of immune and nervous system has been recognized in past, recent studies suggest that ECS function as a bridge between neuronal and immune system. In several ongoing clinical trial studies, the ECS has also been placed in the anti-cancer drugs spotlight. This review summarizes the literature of cannabinoid ligands and their biosynthesis, cannabinoid receptors and their distribution, and the signaling pathways initiated by the binding of cannabinoid ligands to cannabinoid receptors. Further, this review highlights the functional role of cannabinoids and ECS in blood cell development, neuroimmune interactions and associated disorders. Moreover, we highlight the current state of knowledge of cannabinoid ligands as the mediators of neuroimmune interactions, which can be therapeutically effective for neuro-immune disorders and several diseases associated with neuroinflammation.

Cannabidiol and Vitamin D3 Impact on Osteogenic Differentiation of Human Dental Mesenchymal Stem Cells

Background and objective: The aim of the present study was to establish a new differentiation protocol using cannabidiol (CBD) and vitamin D3 (Vit. D3) for a better and faster osteogenic differentiation of dental tissue derived mesenchymal stem cells (MSCs). Materials and methods: MSCs were harvested from dental follicle (DFSCs), dental pulp (DPSCs), and apical papilla (APSCs) of an impacted third molar of a 17-year old patient. The stem cells were isolated and characterized using flow cytometry; reverse transcription polymerase chain reaction (RT-PCR); and osteogenic, chondrogenic, and adipogenic differentiation. The effects of CBD and Vit. D3 on osteogenic differentiation of dental-derived stem cell were evaluated in terms of viability/metabolic activity by alamar test, expression of collagen1A, osteopontin (OP), osteocalcin (OC), and osteonectin genes and by quantification of calcium deposits by alizarin red assay. Results: Stem cell characterization revealed more typical stemness characteristics for DFSCs and DPSCs and atypical morphology and markers expression for APSCs, a phenotype that was confirmed by differences in multipotential ability. The RT-PCR quantification of bone matrix proteins expression revealed a different behavior for each cell type, APSCs having the best response for CBD. DPSCs showed the best osteogenic potential when treated with Vit. D3. Cultivation of DFSC in standard stem cell conditions induced the highest expression of osteogenic genes, suggesting the spontaneous differentiation capacity of these cells. Regarding mineralization, alizarin red assay indicated that DFSCs and APSCs were the most responsive to low doses of CBD and Vit. D3. DPSCs had the lowest mineralization levels, with a slightly better response to Vit. D3. Conclusions: This study provides evidence that DFSCs, DPSCs, and APSCs respond differently to osteoinduction stimuli and that CBD and Vit. D3 can enhance osteogenic differentiation of these types of cells under certain conditions and doses.

Cannabinoid Use in Musculoskeletal Illness: a Review of the Current Evidence

PURPOSE OF REVIEW

The use of cannabinoids has increased since legalization of recreational and medical use in the USA. It is likely that many orthopaedic patients consume cannabinoid products during the traumatic or perioperative period. The purpose of this study was to investigate the pre-clinical data evaluating the mechanism of action of cannabidiol (CBD) and Δ9-Tetrahydrocannabinol (Δ9-THC) and to evaluate the current clinical data on the use of cannabinoids in musculoskeletal illness.

RECENT FINDINGS

Recent pre-clinical studies have demonstrated that cannabinoid use and the endocannabinoid system (ECS) has an important role in bone healing and bone homeostasis. There is data that suggests that the use of cannabidiol (CBD) may increase bone healing, whereas the use of Δ9-Tetrahydrocannabinol (Δ9-THC), the major psychoactive ingredient in marijuana, likely inhibits bone metabolism and repair. The clinical implications and consumption of marijuana by orthopaedic patients have not been thoroughly evaluated. Studies have demonstrated concern for negative cardiovascular and psychiatric effects caused by marijuana use, but have not yet elucidated outcomes in the orthopaedic literature. With the recent increase in advertising of CBD products and legalization of marijuana, it is likely that many orthopaedic patients are consuming cannabinoid products. The clinical implications and consumption of these products are unclear. We need more robust and well-designed clinical studies prior to making further recommendations to our patients on the consumption of these products.

The Effects of Marijuana Use on Lumbar Spinal Fusion

MINI: This study compared clinical and patient-reported outcomes following transforaminal lumbar interbody fusion between patients who use or do not use marijuana. We found that patients who use marijuana are younger, but do not demonstrate any differences in preoperative or postoperative Oswestry disability index scores or rates of fusion.

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The purpose of this study was to evaluate marijuana usage and its effect on outcomes following transforaminal lumbar interbody fusion (TLIF).

SUMMARY OF BACKGROUND DATA

As marijuana becomes legalized throughout the United States, its medicinal and recreational usage is becoming more mainstream. Clinicians currently have little guidance regarding both short-term and long-term effects of marijuana usage on surgical interventions. While the rate of lumbar spinal fusion in the United States continues to grow, the effect of marijuana usage on fusion remains uncertain.

METHODS

One hundred two patients who underwent TLIF performed by the same surgeon were followed for 12 months. Patients were self-reported for marijuana usage (n = 36). Patient reported outcome measures included preoperative Oswestry disability index (ODI), 6-month ODI, and 12-month ODI, as well as length of stay (LOS), complications, return to operating room (OR), revision surgery, and confirmed fusion. Continuous variables were compared using the independent two-sample t test or analysis of variance (ANOVA), whereas categorical variables were analyzed using the chi-square or Fischer exact tests. Adjusted analysis was performed using a multivariate logistic regression model.

RESULTS

Marijuana usage was associated with a younger population (P < 0.001), but showed no difference regarding sex or body mass index compared with the non-usage group. There was no statistically significant difference in complications, return to OR, or revision surgery between groups. When controlling for factors such as age and preoperative ODI, multivariate analysis demonstrated that marijuana usage did not limit postoperative ODI reduction. The marijuana usage group demonstrated shorter LOS (2.42 vs. 3.00 d, P = 0.020). Fusion rates at 12 months were similar between groups (96% vs. 92.3%, P = 0.678). ODI was similar between groups at all time points.

CONCLUSION

Perioperative outcomes were similar in patients who underwent TLIF regardless of marijuana usage.

LEVEL OF EVIDENCE

3.

Characterization of Endocannabinoid System and Interleukin Profiles in Ovine AEC: Cannabinoid Receptors Type-1 and Type-2 as Key Effectors of Pro-Inflammatory Response

Amniotic epithelial cells (AEC) have been proposed as promising clinical candidates for regenerative medicine therapies due to their immunomodulatory capacity. In this context, the endocannabinoid system (ECS) has been identified as mediating the immune-stem cell dialogue, even if no information on AEC is available to date. Therefore, this study was designed to assess whether ECS is involved in tuning the constitutive and lipopolysaccharide (LPS)-induced ovine AEC anti-inflammatory and pro-inflammatory interleukin (IL-10, IL-4, and IL-12) profiles. Firstly, interleukins and ECS expressions were studied at different stages of gestation. Then, the role of cannabinoid receptors 1 and 2 (CB1 and CB2) on interleukin expression and release was investigated in middle stage AEC using selective agonists and antagonists. AEC displayed a degradative more than a synthetic endocannabinoid metabolism during the early and middle stages of gestation. At the middle stage, cannabinoid receptors mediated the balance between pro-inflammatory (IL-12) and anti-inflammatory (IL-4 and IL-10) interleukins. The activation of both receptors mediated an overall pro-inflammatory shift-CB1 reduced the anti-inflammatory and CB2 increased the pro-inflammatory interleukin release, particularly after LPS stimulation. Altogether, these data pave the way for the comprehension of AEC mechanisms tuning immune-modulation, crucial for the development of new AEC-based therapy protocols.

Pharmacological tools to mobilise mesenchymal stromal cells into the blood promote bone formation after surgery

Therapeutic approaches requiring the intravenous injection of autologous or allogeneic mesenchymal stromal cells (MSCs) are currently being evaluated for treatment of a range of diseases, including orthopaedic injuries. An alternative approach would be to mobilise endogenous MSCs into the blood, thereby reducing costs and obviating regulatory and technical hurdles associated with development of cell therapies. However, pharmacological tools for MSC mobilisation are currently lacking. Here we show that β3 adrenergic agonists (β3AR) in combination with a CXCR4 antagonist, AMD3100/Plerixafor, can mobilise MSCs into the blood in mice and rats. Mechanistically we show that reversal of the CXCL12 gradient across the bone marrow endothelium and local generation of endocannabinoids may both play a role in this process. Using a spine fusion model we provide evidence that this pharmacological strategy for MSC mobilisation enhances bone formation.

Neurological Regulation of the Bone Marrow Niche

The bone marrow (BM) hematopoietic niche is the microenvironment where in the adult hematopoietic stem and progenitor cells (HSPCs) are maintained and regulated. This regulation is tightly controlled through direct cell-cell interactions with mesenchymal stromal stem (MSCs) and reticular cells, adipocytes, osteoblasts and endothelial cells, through binding to extracellular matrix molecules and through signaling by cytokines and hematopoietic growth factors. These interactions provide a healthy environment and secure the maintenance of the HSPC pool, their proliferation, differentiation and migration. Recent studies have shown that innervation of the BM and interactions with the peripheral sympathetic neural system are important for maintenance of the hematopoietic niche, through direct interactions with HSCPs or via interactions with other cells of the HSPC microenvironment. Signaling through adrenergic receptors (ARs), opioid receptors (ORs), endocannabinoid receptors (CRs) on HSPCs and MSCs has been shown to play an important role in HSPC homeostasis and mobilization. In addition, a wide range of neuropeptides and neurotransmitters, such as Neuropeptide Y (NPY), Substance P (SP) and Tachykinins, as well as neurotrophins and neuropoietic growth factors have been shown to be involved in regulation of the hematopoietic niche. Here, a comprehensive overview is given of their role and interactions with important cells in the hematopoietic niche, including HSPCs and MSCs, and their effect on HSPC maintenance, regulation and mobilization.

CB1 enhanced the osteo/dentinogenic differentiation ability of periodontal ligament stem cells via p38 MAPK and JNK in an inflammatory environment

Objectives

Periodontitis is an inflammatory immune disease that causes periodontal tissue loss. Inflammatory immunity and bone metabolism are closely related to periodontitis. The cannabinoid receptor I (CB1) is an important constituent of the endocannabinoid system and participates in bone metabolism and inflammation tissue healing. It is unclear whether CB1 affects the mesenchymal stem cell (MSC) function involved in periodontal tissue regeneration. In this study, we revealed the role and mechanism of CB1 in the osteo/dentinogenic differentiation of periodontal ligament stem cells (PDLSCs) in an inflammatory environment.

Materials and methods

Alkaline phosphatase (ALP) activity, Alizarin Red staining, quantitative calcium analysis and osteo/dentinogenic markers were used to assess osteo/dentinogenic differentiation. Real‐time RT‐PCR and Western blotting were employed to detect gene expression.

Results

CB1 overexpression or CB1 agonist (10 µM R‐1 Meth) promoted the osteo/dentinogenic differentiation of PDLSCs. Deletion of CB1 or the application of CB1 antagonist (10 µM AM251) repressed the osteo/dentinogenic differentiation of PDLSCs. The activation of CB1 enhanced the TNF‐α‐ and INF‐γ‐impaired osteo/dentinogenic differentiation potential in PDLSCs. Moreover, CB1 activated p38 MAPK and JNK signalling and repressed PPAR‐γ and Erk1/2 signalling. Inhibition of JNK signalling could block CB1‐activated JNK and p38 MAPK signalling, while CB1 could activate p38 MAPK and JNK signalling, which was inhibited by TNF‐α and INF‐γ stimulation.

Conclusions

CB1 was able to enhance the osteo/dentinogenic differentiation ability of PDLSCs via p38 MAPK and JNK signalling in an inflammatory environment, which might be a potential target for periodontitis treatment.

Opportunities for cannabis in supportive care in cancer

Cannabis has the potential to modulate some of the most common and debilitating symptoms of cancer and its treatments, including nausea and vomiting, loss of appetite, and pain. However, the dearth of scientific evidence for the effectiveness of cannabis in treating these symptoms in patients with cancer poses a challenge to clinicians in discussing this option with their patients. A review was performed using keywords related to cannabis and important symptoms of cancer and its treatments. Literature was qualitatively reviewed from preclinical models to clinical trials in the fields of cancer, human immunodeficiency virus (HIV), multiple sclerosis, inflammatory bowel disease, post-traumatic stress disorder (PTSD), and others, to prudently inform the use of cannabis in supportive and palliative care in cancer. There is a reasonable amount of evidence to consider cannabis for nausea and vomiting, loss of appetite, and pain as a supplement to first-line treatments. There is promising evidence to treat chemotherapy-induced peripheral neuropathy, gastrointestinal distress, and sleep disorders, but the literature is thus far too limited to recommend cannabis for these symptoms. Scant, yet more controversial, evidence exists in regard to cannabis for cancer- and treatment-related cognitive impairment, anxiety, depression, and fatigue. Adverse effects of cannabis are documented but tend to be mild. Cannabis has multifaceted potential bioactive benefits that appear to outweigh its risks in many situations. Further research is required to elucidate its mechanisms of action and efficacy and to optimize cannabis preparations and doses for specific populations affected by cancer.

Cannabinoids and bone regeneration

Bone is a complex tissue with unique properties such as high strength and regeneration capabilities while carrying out multiple functions. Bone regeneration occurs both in physiological situations (bone turnover) and in pathological situations (e.g. fractures), being performed by osteoblasts and osteoclasts. If this process is inadequate, fracture nonunion or aseptic loosening of implants occurs and requires a complex treatment. Exogenous factors are currently used to increase bone regeneration process when needed, such as bisphosphonates and vitamin D, but limitations do exist. Cannabinoid system has been shown to have positive effects on bone metabolism. Cannabinoids at bone level mainly act on two receptors called CB-1 and CB-2, but GPR55, GPR119, TPRV1, TPRV4 receptors may also be involved. The CB-2 receptors are found in bone cells at higher levels compared to other receptors. Endocannabinods represented by anandamide and 2-arachidonoylglycerol, can stimulate osteoblast formation, bone formation and osteoclast activity. CB-2 agonists including HU-308, HU-433, JWH133, and JWH015 can stimulate osteoblast proliferation and activity, while CB-2 antagonists such as AM630 and SR144528 can inhibit osteoclast differentiation and function. CB-1 antagonist AM251 has been shown to inhibit osteoclast differentiation and activity, while GPR55 antagonist cannabidiol increases osteoblast activity and decreases osteoclast function. An optimal correlation of dose, duration, moment of action, and affinity can lead to an increased bone regeneration capacity, with important benefits in many pathological situations which involve bone tissue. As adverse reactions of cannabinoids have not been described in patients under controlled medication, cannabinoids can represent future treatment for bone regeneration.

Decisive role of P42/44 mitogen-activated protein kinase in Δ9-tetrahydrocannabinol-induced migration of human mesenchymal stem cells

In past years, medical interest in Δ⁹-tetrahydrocannabinol (THC), the major psychoactive ingredient of the Cannabis plant, has been renewed due to the elucidation of the endocannabinoid system and diverse other receptor targets involved in biological cannabinoid effects. The present study therefore investigates the impact of THC on the migration of mesenchymal stem cells (MSCs) which are known to be involved in various regenerative processes such as bone healing. Using Boyden chamber assays, THC was found to increase the migration of adipose-derived MSCs. Migration by THC was almost completely suppressed by the CB₁ receptor antagonist AM-251 and to a lesser extent by the CB₂ receptor antagonist AM-630. By contrast, the TRPV1 antagonist capsazepine as well as the G protein-coupled receptor 55 (GRP55) agonist O-1602 did not significantly interfere with the promigratory effect of THC. Furthermore, increased migration by THC was fully suppressed by PD98059, an inhibitor of p42/44 mitogen-activated protein kinase (MAPK) activation, and was accompanied by a time-dependent activation of this pathway accordingly. In line with the migration data, additional inhibitor experiments pointed towards a decisive role of the CB₁ receptor in conferring THC-induced activation of p42/44 MAPK. Collectively, this study demonstrates THC to exert a promigratory effect on MSCs via a CB₁ receptor-dependent activation of p42/44 MAPK phosphorylation. This pathway may be involved in regenerative effects of THC and could be a target of pharmacological intervention.

Collagen and Hydroxyapatite Scaffolds Activate Distinct Osteogenesis Signaling Pathways in Adult Adipose-Derived Multipotent Stromal Cells

Osteogenic cell signaling pathway disruption varies among bone diseases. This investigation was designed to identify adipose-derived multipotent stromal cell (ASC) and bone graft scaffold combinations for local, targeted restoration of gene expression and extracellular matrix (ECM) deposition. Human ASC osteogenesis on bone graft materials was quantified following culture in stromal (S), osteogenic (O), or osteogenic for 48 h followed by stromal medium (OS) to test the two-part hypothesis: (1) identical ASC isolates on distinct bone graft scaffolds demonstrate unique viability, differentiation, ECM production, and gene expression in the same culture conditions; (2) identical ASC-bone graft scaffold combinations have different cell viability, differentiation, ECM production, and gene expression when cultured in S, O, or OS medium. Three commercially available bone graft scaffold materials, type I bovine collagen (C), hydroxyapatite + β-tricalcium phosphate + type I bovine collagen (HT), and β-tricalcium phosphate + type I bovine collagen (CT) were evaluated. Passage 3 ASCs were loaded onto scaffold blocks with a spinner flask bioreactor, and constructs were cultured up to 28 days. Cell viability, gene expression (alkaline phosphatase [ALPL], osteoprotegerin [TNFRSF11B], osteocalcin [BGLAP], cannabinoid receptors type I [CNR1] and II [CNR2], receptor activator of nuclear factor kappa β ligand [TNFSF11]), as well as ECM DNA, collagen, sulfated glycosaminoglycan, and protein content were quantified. Matrix organization was evaluated with scanning electron microscopy. Effects of scaffold, medium, or culture duration on cell viability were minimal. Significantly higher initial ALPL expression decreased with time, while BGLAP expression increased in HT constructs in O medium, and the constructs had the most abundant ECM components and ultrastructural organization. There was a similar, although delayed, pattern of gene expression and greater ECM collagen with less organization in C constructs in O medium. Higher CNR1 expression in C versus higher TNFRSF11B/TNFSF11 expression in HT constructs throughout the study support stimulation of unique osteogenic signaling pathways by identical cell isolates. These results suggest that bone scaffold composition may be used to selectively target specific osteogenic cell signaling pathways in ASC constructs to stimulate ECM deposition based on therapeutic needs.

Heavy Cannabis Use Is Associated With Low Bone Mineral Density and an Increased Risk of Fractures

PURPOSE

To investigate possible associations between recreational cannabis use and bone health in humans.

METHODS

Cross-sectional study of individuals recruited from primary care in the UK between 2011 and 2013. Cases were regular smokers of cannabis divided into moderate (n = 56) and heavy user (n = 144) subgroups depending on whether they reported fewer or more than 5000 cannabis smoking episodes during their lifetime. Controls comprised 114 cigarette smokers.

RESULTS

Heavy cannabis users had lower total hip bone mineral density (mean ± SD Z-score: -0.20 ± 0.9 vs +0.2 ± 0.9, P < .0005), lower spine bone mineral density (-0.5 ± 1.2 vs 0.0 ± 1.2, P < .0005), and lower body mass index (BMI; 26.5 ± 6.0 vs 29.0 ± 7.0, P = .01) than controls. Fracture rate was also increased in heavy users (rate ratio = 2.17; 95% confidence interval, 1.59-2.95; P < .001). When compared with controls, serum cross-linked C-telopeptide of type 1 collagen (CTX) concentrations were raised in heavy cannabis users (0.3 ± 0.1 vs 0.2 ± 0.1 pg/mL, P = .045), as were serum N-terminal propeptide of type 1 procollagen (P1NP) concentrations (47.1 ± 19.2 vs 41.2 ± 17.8 pg/mL, P = .01). Serum total 25-hydroxyvitamin D concentrations were reduced in heavy users compared with controls (25.3 ± 16.8 vs 36.9 ± 26.7 nmol/L, P = .002). Multiple regression analysis revealed that heavy cannabis use was an independent predictor of spine bone mineral density, accounting for 5.4% of the variance (P = .035), and total hip bone mineral density, accounting for 5.8% of the variance (P = .001), but mediation analysis suggested that the effect on spine bone mineral density was indirect and mediated through low body mass index.

CONCLUSIONS

Heavy cannabis use is associated with low bone mineral density, low BMI, high bone turnover, and an increased risk of fracture. Heavy cannabis use negatively impacts on bone health both directly and indirectly through an effect on BMI.

Up-regulation of immunomodulatory effects of mouse bone-marrow derived mesenchymal stem cells by tetrahydrocannabinol pre-treatment involving cannabinoid receptor CB2

Chronic pain is commonly and closely correlated with inflammation. Both cannabinoid signaling and mesenchymal stem cells (MSCs) have been demonstrated to reduce inflammatory pain. Although cannabinoid signaling is essential for mesenchymal stem cell survival and differentiation, little is known about its role in modulatory effect of MSCs on inflammation and pain sensitivity. Here we showed that mouse bone-marrow derived MSCs (BM-MSCs) expressed both cannabinoid receptor type 1 and 2 (CB1 and CB2). CB2 expression level in BM-MSCs increased with their maturation. In addition, we found that tetrahydrocannabinol (THC) activated CB2 receptor and ERK signaling, consequently enhancing the modulation of MSCs on inflammation-associated cytokine release from lipopolysaccharides-stimulated microglia. Consistent with in vitro data, THC pretreatment enhanced the immunomodulatory effects of BM-MSC on thermal hyperalgesia and mechanical allodynia in chronic constriction injury model, by decreasing the release of pro-inflammation cytokines. Our study revealed the crucial role of THC in promoting the immunomodulatory effects of MSCs and proposed a new strategy to alleviate pain based on stem cells therapy.

Cannabidiol Modulates the Immunophenotype and Inhibits the Activation of the Inflammasome in Human Gingival Mesenchymal Stem Cells

Human Gingival Mesenchymal Stem Cells (hGMSCs) are multipotential cells that can expand and differentiate in culture under specific and standardized conditions. In the present study, we have investigated whether in vitro pre-treatment of hGMSCs with Cannabidiol (CBD) can influence their expression profile, improving the therapeutic potential of this cell culture. Following CBD treatment (5 μM) for 24 h, gene expression analysis through Next Generation Sequencing (NGS) has revealed several genes differentially expressed between CBD-treated hGMSCs (CBD-hGMSCs) and control cells (CTR-hGMSCs) that were linked to inflammation and apoptosis. In particular, we have demonstrated that CBD treatment in hGMSCs prevented the activation of the NALP3-inflammasome pathway by suppressing the levels of NALP3, CASP1, and IL18, and in parallel, inhibited apoptosis, as demonstrated by the suppression of Bax. CBD treatment was also able to modulate the expression of the well-known mesenchymal stem cell markers (CD13, CD29, CD73, CD44, CD90, and CD166), and other surface antigens. Specifically, CBD led to the downregulation of genes codifying for antigens involved in the activation of the immune system (CD109, CD151, CD40, CD46, CD59, CD68, CD81, CD82, CD99), while it led to the upregulation of those implicated in the inhibition of the immune responses (CD47, CD55, CD276). In conclusion, the present study will provide a new simple and reproducible method for preconditioning hGMSCs with CBD, before transplantation, as an interesting strategy for improving the hGMSCs molecular phenotype, reducing the risk of immune or inflammatory reactions in the host, and in parallel, for increasing their survival and thus, their long-term therapeutic efficacy.

G protein-coupled receptors in stem cell maintenance and somatic reprogramming to pluripotent or cancer stem cells

G protein-coupled receptors (GPCRs) are a large class of transmembrane receptors categorized into five distinct families: rhodopsin, secretin, adhesion, glutamate, and frizzled. They bind and regulate 80% of all hormones and account for 20-50% of the pharmaceuticals currently on the market. Hundreds of GPCRs integrate and coordinate the functions of individual cells, mediating signaling between various organs. GPCRs are crucial players in tumor progression, adipogenesis, and inflammation. Several studies have also confirmed their central roles in embryonic development and stem cell maintenance. Recently, GPCRs have emerged as key players in the regulation of cell survival, proliferation, migration, and self-renewal in pluripotent (PSCs) and cancer stem cells (CSCs). Our study and other reports have revealed that the expression of many GPCRs is modulated during the generation of induced PSCs (iPSCs) or CSCs as well as during CSC sphere formation. These GPCRs may have crucial roles in the regulation of selfrenewal and other biological properties of iPSCs and CSCs. This review addresses the current understanding of the role of GPCRs in stem cell maintenance and somatic reprogramming to PSCs or CSCs.

Understanding the local actions of lipids in bone physiology

The adult skeleton is a metabolically active organ system that undergoes continuous remodeling to remove old and/or stressed bone (resorption) and replace it with new bone (formation) in order to maintain a constant bone mass and preserve bone strength from micro-damage accumulation. In that remodeling process, cellular balances--adipocytogenesis/osteoblastogenesis and osteoblastogenesis/osteoclastogenesis--are critical and tightly controlled by many factors, including lipids as discussed in the present review. Interest in the bone lipid area has increased as a result of in vivo evidences indicating a reciprocal relationship between bone mass and marrow adiposity. Lipids in bones are usually assumed to be present only in the bone marrow. However, the mineralized bone tissue itself also contains small amounts of lipids which might play an important role in bone physiology. Fatty acids, cholesterol, phospholipids and several endogenous metabolites (i.e., prostaglandins, oxysterols) have been purported to act on bone cell survival and functions, the bone mineralization process, and critical signaling pathways. Thus, they can be regarded as regulatory molecules important in bone health. Recently, several specific lipids derived from membrane phospholipids (i.e., sphingosine-1-phosphate, lysophosphatidic acid and different fatty acid amides) have emerged as important mediators in bone physiology and the number of such molecules will probably increase in the near future. The present paper reviews the current knowledge about: (1°) bone lipid composition in both bone marrow and mineralized tissue compartments, and (2°) local actions of lipids on bone physiology in relation to their metabolism. Understanding the roles of lipids in bone is essential to knowing how an imbalance in their signaling pathways might contribute to bone pathologies, such as osteoporosis.