Mesenchymal stem cells for bone repair and metabolic bone diseases

An Elastin-Derived Composite Matrix for Enhanced Vascularized and Innervated Bone Tissue Reconstruction: From Material Development to Preclinical Evaluation

Despite progress in bone tissue engineering, reconstruction of large bone defects remains an important clinical challenge. Here, a biomaterial designed to recruit bone cells, endothelial cells, and neuronal fibers within the same matrix is developed, enabling bone tissue regeneration. The bioactive matrix is based on modified elastin-like polypeptides (ELPs) grafted with laminin-derived adhesion peptides IKVAV and YIGSR, and the SNA15 peptide for retention of hydroxyapatite (HA) particles. The composite matrix shows suitable porosity, interconnectivity, biocompatibility for endothelial cells, and the ability to support neurites outgrowth by sensory neurons. Subcutaneous implantation leads to the formation of osteoid tissue, characterized by the presence of bone cells, vascular networks, and neuronal structures, while minimizing inflammation. Using a rat femoral condyle defect model, longitudinal micro-CT analysis is performed, which demonstrates a significant increase in the volume of mineralized tissue when using the ELP-based matrix compared to empty defects and a commercially available control (Collapat). Furthermore, visible blood vessel networks and nerve fibers are observed within the lesions after a period of two weeks. By incorporating multiple key components that support cell growth, mineralization, and tissue integration, this ELP-based composite matrix provides a holistic and versatile solution to enhance bone tissue regeneration.

A Comprehensive Study of Meningioma Biomineralization: Morphological, Crystallographic, and Immunohistochemical Aspects

Biomineralization of brain tissues occurs both in normal and pathological conditions. Dura mater biomineralization is widespread and occurs in 1-72% of cases, depending on the patient's age and research method. The amount of biomineral deposits under the conditions of tumor growth in the meninges only increases, reaching 100% in the case of psammomatous meningiomas. Since calcifications are often found in the meninges, the problem of differential diagnosis with calcified meningiomas arises. A total of 30 samples of meningiomas with signs of biomineralization-dense structure, characteristic crunch, psammoma bodies (group I) and 30 samples of meningiomas without any signs of biomineralization were examined as controls (group II). To detect pathological biomineralization, the meningioma tissue was studied using the methods of macroscopic description, histology, histochemistry, and immunohistochemistry, scanning electron microscopy with microanalysis, and transmission electron microscopy. A significantly higher level of caspase3 and features of the expression of osteoblastic markers (a lower level of OPG expression and a higher level of the presence of RANKL in group I, the absence of fluctuations in the expression of SPARC) may indicate a dystrophic type of development of biomineral deposits in meningiomas.

New Perspectives of Therapies in Osteogenesis Imperfecta-A Literature Review

(1) Background: Osteogenesis imperfecta (OI) is a rare skeletal dysplasia characterized as a heterogeneous disorder group with well-defined phenotypic and genetic features that share uncommon bone fragility. The current treatment options, medical and orthopedic, are limited and not efficient enough to improve the low bone density, bone fragility, growth, and mobility of the affected individuals, creating the need for alternative therapeutic agents. (2) Methods: We searched the medical database to find papers regarding treatments for OI other than conventional ones. We included 45 publications. (3) Results: In reviewing the literature, eight new potential therapies for OI were identified, proving promising results in cells and animal models or in human practice, but further research is still needed. Bone marrow transplantation is a promising therapy in mice, adults, and children, decreasing the fracture rate with a beneficial effect on structural bone proprieties. Anti-RANKL antibodies generated controversial results related to the therapy schedule, from no change in the fracture rate to improvement in the bone mineral density resorption markers and bone formation, but with adverse effects related to hypercalcemia. Sclerostin inhibitors in murine models demonstrated an increase in the bone formation rate and trabecular cortical bone mass, and a few human studies showed an increase in biomarkers and BMD and the downregulation of resorption markers. Recombinant human parathormone and TGF-β generated good results in human studies by increasing BMD, depending on the type of OI. Gene therapy, 4-phenylbutiric acid, and inhibition of eIF2α phosphatase enzymes have only been studied in cell cultures and animal models, with promising results. (4) Conclusions: This paper focuses on eight potential therapies for OI, but there is not yet enough data for a new, generally accepted treatment. Most of them showed promising results, but further research is needed, especially in the pediatric field.

Effects of aligned PLGA/SrCSH composite scaffolds on in vitro growth and osteogenic differentiation of human mesenchymal stem cells

Strontium (Sr) has important functions in bone remodeling. Incorporating strontium-doped α-calcium sulfate hemihydrate (SrCSH) into poly(lactic-co-glycolic acid) (PLGA) fibrous scaffolds were expected to increase its bio-activity and provide a potential material for bone tissue engineering. In the present study, Sr-containing aligned PLGA/SrCSH fibrous scaffolds similar to the architecture of natural bone were prepared via wet spinning. CCK-8 assay revealed that Sr-containing scaffolds possessed better bioactivity and supported favorable cell growth effectively. The aligned PLGA/SrCSH fibers exerted a contact effect on cell attachment, inducing regular cell alignment and influencing a series of cell behaviors. Releasing of high concentration Sr from a-PLGA/SrCSH scaffolds could induce high expression levels of BMP-2, increase ALP activity and upregulate RUNX-2 expression, and further promote the expressions of COL-I and OCN and the maximum mineralization. This study demonstrated that Sr and ordered structure in a-PLGA/SrCSH fibrous scaffolds could synergistically enhance the osteogenic differentiation of umbilical cord mesenchymal stem cells (UCMSCs) by regulating cell arrangement and expressions of osteogenic genes.

Bone Marrow Stromal Cells Sorted by Semiconducting Polymer Nanodots for Bone Repair

The use of bone marrow stromal cells (BMSCs) for bone defect repair has shown great promise due to their differentiation potential. However, isolating the BMSCs from various cell types within the bone marrow remains challenging. To tackle this issue, we utilized semiconducting polymer dots (Pdots) as markers to select the BMSCs within a specific time frame. The therapeutic efficacy of the obtained Pdot-labeled BMSCs was assessed in a bone defect model. Initially, we evaluated the binding capacity of the Pdots with four different types of cells present in the bone marrow including BMSCs, osteoblasts, macrophages, and vascular endothelial cells, in vitro. Notably, BMSCs showed the most rapid uptake of the Pdots, being labeled within only one h of coculture, while other cells took four h to become labeled. Moreover, by colocalizing the Pdots with Prrx1, Sca-1, OSX, F480, and CD105 in the bone marrow cells of monocortical tibial defect (MTD) mice in vivo, we determined the proportions of BMSCs, macrophages, and vascular endothelial cells among all labeled cells from 1 to 8 h after the Pdots injection. It was found that BMSCs have the highest proportion (92%) among all labeled cells extracted after 1 h of Pdots injection. The therapeutic efficacy of the obtained Pdots-labeled BMSCs (1 h) was assessed in a bone defect model. Results showed that the new bone accrual was significantly increased in the treatment of Pdots-labeled BMSCs compared to the bone marrow cell-treated group. Our study revealed that BMSCs screened by the Pdots could improve bone defect repair, suggesting a promising application of the Pdots in bone healing.

Controlling differentiation of stem cells via bioactive disordered cues

Ideal bone tissue engineering is to induce bone regeneration through the synergistic integration of biomaterial scaffolds, bone progenitor cells, and bone-forming factors. Biomimetic scaffolds imitate the native extracellular matrix (ECM) and are often utilized in vitro as analogues of the natural ECM to facilitate investigations of cell-ECM interactions and processes. In vivo, the cellular microenvironment has a crucial impact on regulating cell behavior and functions. A PET surface was activated and then functionalized with mimetic peptides to promote human mesenchymal stem cell (hMSC) adhesion and differentiation into an osteogenic lineage. Spray technology was used to randomly micropattern peptides (RGD and BMP-2 mimetic peptides) on the PET surface. The distribution of the peptides grafted on the surface, the roughness of the surfaces and the chemistry of the surfaces in each step of the treatment were ascertained by atomic force microscopy, fluorescence microscopy, time-of-flight secondary ion mass spectrometry, Toluidine Blue O assay, and X-ray photoelectron spectroscopy. Subsequently, cell lineage differentiation was evaluated by quantifying the expression of immunofluorescence markers: osteoblast markers (Runx-2, OPN) and osteocyte markers (E11, DMP1, and SOST). In this article, we hypothesized that a unique combination of bioactive micro/nanopatterns on a polymer surface improves the rate of morphology change and enhances hMSC differentiation. In DMEM, after 14 days, disordered micropatterned surfaces with RGD and BMP-2 led to a higher osteoblast marker expression than surfaces with a homogeneous dual peptide conjugation. Finally, hMSCs cultured in osteogenic differentiation medium (ODM) showed accelerated cell differentiation. In ODM, our results highlighted the expression of osteocyte markers when hMSCs were seeded on PET surfaces with random micropatterns.

Fresh Umbilical Cord Blood-A Source of Multipotent Stem Cells, Collection, Banking, Cryopreservation, and Ethical Concerns

Umbilical cord blood (UCB) is a rich source of hematopoietic cells that can be used to replace bone marrow components. Many blood disorders and systemic illnesses are increasingly being treated with stem cells as regenerative medical therapy. Presently, collected blood has been stored in either public or private banks for allogenic or autologous transplantation. Using a specific keyword, we used the English language to search for relevant articles in SCOPUS and PubMed databases over time frame. According to our review, Asian countries are increasingly using UCB preservation for future use as regenerative medicine, and existing studies indicate that this trend will continue. This recent literature review explains the methodology of UCB collection, banking, and cryopreservation for future clinical use. Between 2010 and 2022, 10,054 UCB stem cell samples were effectively cryopreserved. Furthermore, we have discussed using Mesenchymal Stem Cells (MSCs) as transplant medicine, and its clinical applications. It is essential for healthcare personnel, particularly those working in labor rooms, to comprehend the protocols for collecting, transporting, and storing UCB. This review aims to provide a glimpse of the details about the UCB collection and banking processes, its benefits, and the use of UCB-derived stem cells in clinical practice, as well as the ethical concerns associated with UCB, all of which are important for healthcare professionals, particularly those working in maternity wards; namely, the obstetrician, neonatologist, and anyone involved in perinatal care. This article also highlights the practical and ethical concerns associated with private UCB banks, and the existence of public banks. UCB may continue to grow to assist healthcare teams worldwide in treating various metabolic, hematological, and immunodeficiency disorders.

Lipoplex-Functionalized Thin-Film Surface Coating Based on Extracellular Matrix Components as Local Gene Delivery System to Control Osteogenic Stem Cell Differentiation

A gene-activated surface coating is presented as a strategy to design smart biomaterials for bone tissue engineering. The thin-film coating is based on polyelectrolyte multilayers composed of collagen I and chondroitin sulfate, two main biopolymers of the bone extracellular matrix, which are fabricated by layer-by-layer assembly. For further functionalization, DNA/lipid-nanoparticles (lipoplexes) are incorporated into the multilayers. The polyelectrolyte multilayer fabrication and lipoplex deposition are analyzed by surface sensitive analytical methods that demonstrate successful thin-film formation, fibrillar structuring of collagen, and homogenous embedding of lipoplexes. Culture of mesenchymal stem cells on the lipoplex functionalized multilayer results in excellent attachment and growth of them, and also, their ability to take up cargo like fluorescence-labelled DNA from lipoplexes. The functionalization of the multilayer with lipoplexes encapsulating DNA encoding for transient expression of bone morphogenetic protein 2 induces osteogenic differentiation of mesenchymal stem cells, which is shown by mRNA quantification for osteogenic genes and histochemical staining. In summary, the novel gene-functionalized and extracellular matrix mimicking multilayer composed of collagen I, chondroitin sulfate, and lipoplexes, represents a smart surface functionalization that holds great promise for tissue engineering constructs and implant coatings to promote regeneration of bone and other tissues.

99mTc-polyphosphonate labelling - Enhancement of a novel method for the quantification of osteogenic differentiation of MSCs in vitro

Bone tissue engineering is a fast-growing field in regenerative medicine. Consequently, there is a high demand for new, fast and reliable methods to track and quantify the osteogenic differentiation of cells. Recently, a novel method was published to non-destructively quantify the hydroxyapatite content of monolayer and 3-dimensional mesenchymal stem cell cultures using the ability of ^99mTechnetium-methylene diphosphonate (MDP), a well-established tracer in clinical nuclear medicine, to bind to newly synthesized hydroxyapatite. In the present study, two other commonly used ^99mTechnetium tracers, 2,3-dicarboxypropane-1,1-diphosphonate (DPD) and hydroxydiphosphonate (HDP), were evaluated to see if they could also be used for the same purpose. Furthermore, we investigated if labelling at various timepoints influenced the effectiveness of the labelling. The results were analysed using one-factor ANOVA followed by Bonferroni post-hoc testing. This revealed a highly significant difference between the three osteogenic groups at each timepoint compared to their corresponding negative controls. However, there was no statistically significant difference between the three different tracers (MDP, DPD, HDP) in the osteogenic groups. Therefore all three tracers are of similar value when quantifying the extracellular hydroxylapatite content in osteogenic stem cells cultures.

Osteogenic enhancement of modular ceramic nanocomposites impregnated with human dental pulp stem cells: an approach for bone repair and regenerative medicine

Background/aim

Human dental pulp-derived mesenchymal stem cells (hDP-MSCs) are a promising source of progenitor cells for bone tissue engineering. Nanocomposites made of calcium phosphate especially hydroxyapatite (HA) offer an impressive solution for orthopedic and dental implants. The combination of hDP-MSCs and ceramic nanocomposites has a promising therapeutic potential in regenerative medicine. Despite the calcium phosphate hydroxyapatite (HA)-based nanocomposites offer a good solution for orthopedic and dental implants, the heavy load-bearing clinical applications require higher mechanical strength, which is not of the HA’ properties that have low mechanical strength. Herein, the outcomes of using fabricated ceramic nanocomposites of hydroxyapatite/titania/calcium silicate mixed at different ratios (C1, C2, and C3) and impregnated with hDP-MSCs both in in vitro cultures and rabbit model of induced tibial bone defect were investigated. Our aim is to find out a new approach that would largely enhance the osteogenic differentiation of hDP-MSCs and has a therapeutic potential in bone regeneration.

Subjects and methods

Human DP-MSCs were isolated from the dental pulp of the third molar and cultured in vitro. Alizarin Red staining was performed at different time points to assess the osteogenic differentiation. Flow cytometer was used to quantify the expression of hDP-MSCs unique surface markers. Rabbits were used as animal models to evaluate the therapeutic potential of osteogenically differentiated hDP-MSCs impregnated with ceramic nanocomposites of hydroxyapatite/tatiana/calcium silicate (C1, C2, and C3). Histopathological examination and scanning electron microscopy (SEM) were performed to evaluate bone healing potential in the rabbit induced tibial defects three weeks post-transplantation.

Results

The hDP-MSCs showed high proliferative and osteogenic potential in vitro culture. Their osteogenic differentiation was accelerated by the ceramic nanocomposites’ scaffold and revealed bone defect’s healing in transplanted rabbit groups compared to control groups. Histopathological and SEM analysis of the transplanted hDP-MSCs/ceramic nanocomposites showed the formation of new bone filling in the defect area 3 weeks post-implantation. Accelerate osseointegration and enhancement of the bone-bonding ability of the prepared nanocomposites were also confirmed by SEM.

Conclusions

The results strongly suggested that ceramic nanocomposites of hydroxyapatite/ titania /calcium silicate (C1, C2, and C3) associated with hDP-MSCs have a therapeutic potential in bone healing in a rabbit model. Hence, the combined osteogenic system presented here is recommended for application in bone tissue engineering and regenerative medicine.

A chemically defined biomimetic surface for enhanced isolation efficiency of high-quality human mesenchymal stromal cells under xenogeneic/serum-free conditions

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) are one of the most frequently used cell types in regenerative medicine and cell therapy. Generating sufficient cell numbers for MSC-based therapies is constrained by (i) their low abundance in tissues of origin, which imposes the need for significant ex vivo cell expansion; (ii) donor-specific characteristics, including MSC frequency/quality, that decline with disease state and increasing age; and (iii) cellular senescence, which is promoted by extensive cell expansion and results in decreased therapeutic functionality. The final yield of a manufacturing process is therefore primarily determined by the applied isolation procedure and its efficiency in isolating therapeutically active cells from donor tissue. To date, MSCs are predominantly isolated using media supplemented with either serum or its derivatives, which poses safety and consistency issues.

METHODS

To overcome these limitations while enabling robust MSC production with constant high yield and quality, the authors developed a chemically defined biomimetic surface coating called isoMATRIX (denovoMATRIX GmbH, Dresden, Germany) and tested its performance during isolation of MSCs.

RESULTS

The isoMATRIX facilitates the isolation of significantly higher numbers of MSCs in xenogeneic (xeno)/serum-free and chemically defined conditions. The isolated cells display a smaller cell size and higher proliferation rate than those derived from a serum-containing isolation procedure and a strong immunomodulatory capacity. The high proliferation rates can be maintained up to 5 passages after isolation and cells even benefit from a switch towards a proliferation-specific MSC matrix (myMATRIX MSC) (denovoMATRIX GmbH, Dresden, Germany).

CONCLUSION

In sum, isoMATRIX promotes enhanced xeno/serum-free and chemically defined isolation of human MSCs and supports consistent and reliable cell performance for improved stem cell-based therapies.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

The Identification of Marker Genes for Predicting the Osteogenic Differentiation Potential of Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) have the potential to differentiate into a variety of mature cell types and are a promising source of regenerative medicine. The success of regenerative medicine using MSCs strongly depends on their differentiation potential. In this study, we sought to identify marker genes for predicting the osteogenic differentiation potential by comparing ilium MSC and fibroblast samples. We measured the mRNA levels of 95 candidate genes in nine ilium MSC and four fibroblast samples before osteogenic induction, and compared them with alkaline phosphatase (ALP) activity as a marker of osteogenic differentiation after induction. We identified 17 genes whose mRNA expression levels positively correlated with ALP activity. The chondrogenic and adipogenic differentiation potentials of jaw MSCs are much lower than those of ilium MSCs, although the osteogenic differentiation potential of jaw MSCs is comparable with that of ilium MSCs. To select markers suitable for predicting the osteogenic differentiation potential, we compared the mRNA levels of the 17 genes in ilium MSCs with those in jaw MSCs. The levels of 7 out of the 17 genes were not substantially different between the jaw and ilium MSCs, while the remaining 10 genes were expressed at significantly lower levels in jaw MSCs than in ilium MSCs. The mRNA levels of the seven similarly expressed genes were also compared with those in fibroblasts, which have little or no osteogenic differentiation potential. Among the seven genes, the mRNA levels of IGF1 and SRGN in all MSCs examined were higher than those in any of the fibroblasts. These results suggest that measuring the mRNA levels of IGF1 and SRGN before osteogenic induction will provide useful information for selecting competent MSCs for regenerative medicine, although the effectiveness of the markers is needed to be confirmed using a large number of MSCs, which have various levels of osteogenic differentiation potential.

Morphology of the Myocardium after Experimental Bone Tissue Trauma and the Use of Extracellular Vesicles Derived from Mesenchymal Multipotent Stromal Cells

The effect of extracellular vesicles (EVs) of various origins on the heart structures in the time of health and disease has been well studied. At the same time, data on the distribution of EVs throughout the body after introduction into the tissues and the possibility of the influence of these EVs on organs distant from the injection site are practically absent. It is also necessary to note a certain inconsistency in the results of various researchers: from articles on the direct absorption of EVs derived from mesenchymal multipotent stromal cells (MSC EVs) by cardiomyocytes to the data that the heart is inherently immune to drug delivery mediated by nanoparticles. In this regard, the morphological changes in the myocardium of outbred rabbits of both sexes weighing 3–4 kg were studied at various times after experimental trauma of the bone tissue in the proximal condyle of the tibia (PCT) and the use of MSC EVs. As a result of modeling the PCT defect, rabbits develop myocardial edema in the heart muscle by the 3rd day, their lymphatic vessels expand, and then, on the 7th day, the blood vessels become dilated. In the myocardium, the relative and absolute contents of neutrophils, erythrocytes, and macrophages increase, but the percentage of lymphocytes decreases. By day 10, almost all of these changes return to their initial values. The detected transformations of the myocardium are most likely due to the ingress of detritus with the blood flow from the PCT. The use of MSC EVs to influence the regeneration of damaged tissue of PCT promotes earlier dilatation of the blood vessels of the heart with pronounced diapedesis of erythrocytes or even hemorrhages, prolongation of edema, the formation of blood clots in vessels with obliteration of their lumen, sclerotic transformation of vascular walls and paravascular tissues. In the myocardium, the number density of neutrophils, the percentage of lymphocytes, and neutrophils become smaller, with a simultaneous increase in the relative numbers of erythrocytes and macrophages, and changes in the content of macrophages remained until the end of the observation—up to 10 days after the surgery. The discovered effect of MSC EVs is most likely associated with the suppression of the activity of the inflammatory process in the PCT area, which, in turn, was caused by a longer ingress of detritus with blood flow into the myocardium. The absence of statistically significant differences between changes in the myocardium of the left and right ventricles may indicate that both detritus from the surgical site and MSC EVs affect the heart spreading through the coronary artery system.

Development of Injectable Hydroxyapatite/2-(dimethylamino)Ethyl Methacrylate/Polyvinylpyrrolidone Aqua-Hydrogel System to Repair of the Shoulder Joint Head for Hemiarthroplasty

This study aimed to develop osteogenic structure assembly for modular bone treatment presentations, effect of 2-(dimethylamino)ethyl methacrylate and polyvinyl pyrrolidone combination as cell adhesive molecule with hydroxyapatite-based composite as osteoconductive constituent was inspected on bone fracture repair. The prepared injectable composite hydrogel showed significantly improved mechanical stability. The ternary composite gel was characterized for functional group modifications and chemical interactions using Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Moreover, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses were performed to observe surface appearances of the hydrogel. The hydroxyapatite/2-(dimethylamino)ethyl methacrylate/poly-N-vinyl-2-pyrrolidone hydrogel played key role in supporting osteoblastic cell spread due to their bioactivity and strength abilities. The present findings revealed the significance of hydroxyapatite concentration on proliferation and osteogenic purpose of the cells. The developed performances of hydrogel have been improved cell proliferation and functions to repair bone fracture.

Bone Marrow-Derived Mesenchymal Stem Cells Migrate toward Hormone-Insensitive Prostate Tumor Cells Expressing TGF-β via N-Cadherin

The prostate tumor microenvironment plays important roles in the metastasis and hormone-insensitive re-growth of tumor cells. Bone marrow-derived mesenchymal stem cells (BM-MSCs) are recruited into prostate tumors to facilitate tumor microenvironment formation. However, the specific intrinsic molecules mediating BM-MSCs’ migration to prostate tumors are unknown. BM-MSCs’ migration toward a conditioned medium (CM) of hormone-insensitive (PC3 and DU145) or hormone-sensitive (LNCaP) prostate tumor cells was investigated using a three-dimensional cell migration assay and a transwell migration assay. PC3 and DU145 expressed transforming growth factor-β (TGF-β), but LNCaP did not. Regardless of TGF-β expression, BM-MSCs migrated toward the CM of PC3, DU145, or LNCaP. The CM of PC3 or DU145 expressing TGF-β increased the phosphorylation of Smad2/3 in BM-MSCs. Inactivation of TGF-β signaling in BM-MSCs using TGF-β type 1 receptor (TGFBR1) inhibitors, SB505124, or SB431542 did not allow BM-MSCs to migrate toward the CM. The CM of PC3 or DU145 enhanced N-cadherin expression on BM-MSCs, but the LNCaP CM did not. SB505124, SB431542, and TGFBR1 knockdown prevented an increase in N-cadherin expression. N-cadherin knockdown inhibited the collective migration of BM-MSCs toward the PC3 CM. We identified N-cadherin as a mediator of BM-MSCs’ migration toward hormone-insensitive prostate tumor cells expressing TGF-β and introduced a novel strategy for controlling and re-engineering the prostate tumor microenvironment.

Modern approaches on stem cells and scaffolding technology for osteogenic differentiation and regeneration

The process of bone repair has always been a natural mystery. Although bones do repair themselves, supplemental treatment is required for the initiation of the self-regeneration process. Predominantly, surgical procedures are employed for bone regeneration. Recently, cell-based therapy for bone regeneration has proven to be more effective than traditional methods, as it eliminates the immune risk and painful surgeries. In clinical trials, various stem cells, especially mesenchymal stem cells, have shown to be more efficient for the treatment of several bone-related diseases, such as non-union fracture, osteogenesis imperfecta, osteosarcoma, and osteoporosis. Furthermore, the stem cells grown in a suitable three-dimensional scaffold support were found to be more efficient for osteogenesis. It has been shown that the three-dimensional bioscaffolds support and simulate an in vivo environment, which helps in differentiation of stem cells into bone cells. Bone regeneration in patients with bone disorders can be improved through modification of stem cells with several osteogenic factors or using stem cells as carriers for osteogenic factors. In this review, we focused on the various types of stem cells and scaffolds that are being used for bone regeneration. In addition, the molecular mechanisms of various transcription factors, signaling pathways that support bone regeneration and the senescence of the stem cells, which limits bone regeneration, have been discussed.

Artemisinin Reverses Glucocorticoid-Induced Injury in Bone Marrow-Derived Mesenchymal Stem Cells through Regulation of ERK1/2-CREB Signaling Pathway

Glucocorticoids are the most common cause of secondary osteoporosis, which affects both women (pre- and postmenopausal) and men. In cases of prolonged treatment, glucocorticoids promote the loss and inactivation of the differentiational function of bone marrow mesenchymal stromal cells (BMSCs), risking the development of skeletal system diseases such as osteoporosis. This study reports for the first time the protective effect of the antimalarial artemisinin against glucocorticoid-induced insults on primary cultured rat BMSCs. At relatively low concentrations, artemisinin treatment improved BMSC survival by promoting a decline of reactive oxygen species (ROS) production that correlated with the decrease of caspase-3 activation, LDH release, mitochondrial membrane potential (Δψm) loss, and apoptosis induced by dexamethasone (DEXA). In addition, artemisinin improved the osteogenic differentiation of DEXA-damaged cells. DEXA inhibited extracellular-signal-regulated kinase 1/2 (ERK1/2) and cAMP response element binding protein (CREB) phosphorylation, and artemisinin treatment promoted their activation in a concentration-dependent manner. PD98059, the specific inhibitor of the ERK1/2 pathway, blocked ERK1/2 phosphorylation and artemisinin protection. Similarly, siCREB attenuated the protective effect of artemisinin, strongly suggesting the involvement of the ERK1/2-CREB pathway in the protective action of artemisinin against DEXA-induced damage in BMSCs. In addition, we found that the expression of antiapoptotic protein B-cell lymphoma 2 protein (BCL-2) was also upregulated by artemisinin. These studies demonstrate the therapeutic potential of artemisinin in the survival improvement of BMSCs exposed to glucocorticoid-induced apoptosis and suggest that artemisinin-mediated protection may occur via the activation of ERK1/2-CREB signaling pathway.

Chromium Oxide Nanoparticle Impaired Osteogenesis and Cellular Response to Mechanical Stimulus

Background

Release of metallic wear particles from hip replacement implants is closely associated with aseptic loosening that affects the functionality and survivorship of the prostheses. Chromium oxide nanoparticles (CrNPs) are the dominant form of the wear particles found in the periprosthetic tissues. Whether CrNPs play a role in the clinically observed particle-induced osteolysis, tissue inflammatory reactions and functional activities of human mesenchymal stem cells (MSCs) remain unknown.

Methods

A tibia-defect rat model, cytotoxicity assays and flow cytometry were applied to study the effect of CrNPs on MSCs survival and macrophage inflammatory response. Also, oscillatory fluid flow stimulation was used to analyse the osteogenic differentiation of MSCs while treated by CrNPs. In addition, the influence of CrNPs on MSC biomechanical properties was determined via atomic force microscope (AFM) and fluorescence microscopy.

Results

It was found that implantation of CrNPs significantly decreased bone formation in vivo. CrNPs had no obvious effects on inflammatory cytokines release of U937 macrophages. Additionally, CrNPs did not interfere with MSCs osteogenic differentiation under static culture. However, the upregulated osteogenic differentiation of MSCs due to fluid flow stimulation was reduced by CrNPs in a dose-dependent manner. Moreover, osteogenic gene expression of OPN, Cox2 and Rnux2 after mechanical stimulation was also decreased by CrNPs treatments. Furthermore, cell elasticity and adhesion force of MSCs were affected by CrNPs over 3 days of exposure. We further verified that these effects of CrNPs could be associated with its interruption on cell mechanical properties.

Conclusion

The results demonstrated that CrNPs impaired cellular response to mechanical stimulus and osteogenesis without noticeable effects on the survival of the human MSCs.

Fabrication techniques involved in developing the composite scaffolds PCL/HA nanoparticles for bone tissue engineering applications

A fine-tuned combination of scaffolds, biomolecules, and mesenchymal stem cells (MSCs) is used in tissue engineering to restore the function of injured bone tissue and overcome the complications associated with its regeneration. For two decades, biomaterials have attracted much interest in mimicking the native extracellular matrix of bone tissue. To this aim, several approaches based on biomaterials combined with MSCs have been amply investigated. Recently, hydroxyapatite (HA) nanoparticles have been incorporated with polycaprolactone (PCL) matrix as a suitable substitute for bone tissue engineering applications. This review article aims at providing a brief overview on PCL/HA composite scaffold fabrication techniques such as sol-gel, rapid prototyping, electro-spinning, particulate leaching, thermally induced phase separation, and freeze-drying, as suitable approaches for tailoring morphological, mechanical, and biodegradability properties of the scaffolds for bone tissues. Among these methods, the 3D plotting method shows improvements in pore architecture (pore size of ≥600 µm and porosity of 92%), mechanical properties (higher than 18.38 MPa), biodegradability, and good bioactivity in bone tissue regeneration.

Mini review: Biomaterials in repair and regeneration of nerve in a volumetric muscle loss

Volumetric muscle loss (VML) following a severe trauma or injury is beyond the intrinsic regenerative capacity of muscle tissues, and hence interventional therapy is required. Extensive muscle loss concomitant with damage to neuromuscular components overwhelms the muscles' remarkable regenerative capacity. The loss of nervous and vascular tissue leads to further damage and atrophy, so a combined treatment for neuromuscular junction (NMJ) along with the volumetric muscle regeneration is important. There have been immense advances in the field of tissue engineering for skeletal muscle tissue and peripheral nerve regeneration, but very few address the interdependence of the tissues and the need for combined therapies to repair and regenerate fully functional muscle tissue. This review addresses the problem and presents an overview of the biomaterials that have been studied for tissue engineering of neuromuscular tissues associated with skeletal muscles.

Emerging marine derived nanohydroxyapatite and their composites for implant and biomedical applications

Implant materials must mimic natural human bones with biocompatibility, osteoconductivity and mechanical stability to successfully replace damaged or disease-affected bones. Synthetic hydroxyapatite was incorporated with bioglass to mimic natural bones for replacing conventional implant materials which has led to certain toxicity issues. Hence, hydroxyapatite (HAp) are recently gaining applicational importance as they are resembling the structure and function of natural bones. Further, nanosized HAp is under extensive research to utilize them as a potential replacement for traditional implants with several exclusive properties. However, chemical synthesis of nano-HAp exhibited toxicity towards normal and healthy cells. Recently, biogenic Hap synthesis from marine and animal sources are introduced as a next generation implant materials, due to their mineral ion and significant porous architecture mediated biocompatibility and bone bonding ability, compared to synthetic HAp. Thus, the purpose of the paper is to give a bird's eye view into the conventional approaches for fabricating nano-HAp, its limitations and the significance of using marine organisms and marine food wastes as a precursor for biogenic nano-Hap production. Moreover, in vivo and in vitro analyses of marine source derived nano-HAp and their potential biomedical applications were also discussed.

Multipotent Stromal Cell Extracellular Vesicle Distribution in Distant Organs after Introduction into a Bone Tissue Defect of a Limb

When administered intravenously, extracellular vesicles derived from multipotent stromal cells (MSC EVs) immediately pass through the lungs along with the blood and regularly spread to all organs. When administered intraperitoneally, they are absorbed either into the blood or into the lymph and are quickly disseminated throughout the body. The possibility of generalized spread of MSC EVs to distant organs in case of local intratissular administration remains unexplored. However, it is impossible to exclude MSC EV influence on tissues distant from the injection site due to the active or passive migration of these injected nanoparticles through the vessels. The research is based on findings obtained when studying the samples of lungs, heart, spleen, and liver of outbred rabbits of both sexes weighing 3-4 kg at various times after the injection of EVs derived from MSCs of bone marrow origin and labeled by PKH26 into an artificially created defect of the proximal condyle of the tibia. MSC EVs were isolated by serial ultracentrifugation and characterized by transmission electron microscopy and flow cytometry. After the introduction of MSC EVs into the damaged proximal condyle of the tibia of rabbits, these MSC EVs can be found most frequently in the lungs, myocardium, liver, and spleen. MSC EVs enter all of these organs with the blood flow. The lungs contained the maximum number of labeled MSC EVs; moreover, they were often associated with detritus and were located in the lumen of the alveoli. In the capillary network of various organs except the myocardium, MSC EVs are adsorbed by paravasal phagocytes; in some cases, specifically labeled small dust-like objects can be detected throughout the entire experiment-up to ten days of observation. Therefore, we can conclude that the entire body, including distant organs, is effected both by antigenic detritus, which appeared in the bloodstream after extensive surgery, and MSC EVs introduced from the outside.

Hallmarks of aging and immunosenescence: Connecting the dots

Aging is a natural physiological process that features various and variable challenges, associated with loss of homeostasis within the organism, often leading to negative consequences for health. Cellular senescence occurs when cells exhaust the capacity to renew themselves and their tissue environment as the cell cycle comes to a halt. This process is influenced by genetics, metabolism and extrinsic factors. Immunosenescence, the aging of the immune system, is a result of the aging process, but can also in turn act as a secondary inducer of senescence within other tissues. This review aims to summarize the current state of knowledge regarding hallmarks of aging in relation to immunosenescence, with a focus on aging-related imbalances in the medullary environment, as well as the components of the innate and adaptive immune responses. Aging within the immune system alters its functionality, and has consequences for the person's ability to fight infections, as well as for susceptibility to chronic diseases such as cancer and cardiovascular disease. The senescence-associated secretory phenotype is described, as well as the involvement of this phenomenon in the paracrine induction of senescence in otherwise healthy cells. Inflammaging is discussed in detail, along with the comorbidities associated with this process. A knowledge of these processes is required in order to consider possible targets for the application of senotherapeutic agents - interventions with the potential to modulate the senescence process, thus prolonging the healthy lifespan of the immune system and minimizing the secondary effects of immunosenescence.

Biological Characteristics and Osteogenic Differentiation of Ovine Bone Marrow Derived Mesenchymal Stem Cells Stimulated with FGF-2 and BMP-2

Cell-based therapies using mesenchymal stem cells (MSCs) are a promising tool in bone tissue engineering. Bone regeneration with MSCs involves a series of molecular processes leading to the activation of the osteoinductive cascade supported by bioactive factors, including fibroblast growth factor-2 (FGF-2) and bone morphogenetic protein-2 (BMP-2). In this study, we examined the biological characteristics and osteogenic differentiation potential of sheep bone marrow MSCs (BM-MSCs) treated with 20 ng/mL of FGF-2 and 100 ng/mL BMP-2 in vitro. The biological properties of osteogenic-induced BM-MSCs were investigated by assessing their morphology, proliferation, phenotype, and cytokine secretory profile. The osteogenic differentiation was characterized by Alizarin Red S staining, immunofluorescent staining of osteocalcin and collagen type I, and expression levels of genetic markers of osteogenesis. The results demonstrated that BM-MSCs treated with FGF-2 and BMP-2 maintained their primary MSC properties and improved their osteogenic differentiation capacity, as confirmed by increased expression of osteocalcin and collagen type I and upregulation of osteogenic-related gene markers BMP-2, Runx2, osterix, collagen type I, osteocalcin, and osteopontin. Furthermore, sheep BM-MSCs produced a variety of bioactive factors involved in osteogenesis, and supplementation of the culture medium with FGF-2 and BMP-2 affected the secretome profile of the cells. The results suggest that sheep osteogenic-induced BM-MSCs may be used as a cellular therapy to study bone repair in the preclinical large animal model.

The Extracts of Human Fetal Brain Induce the Differentiation of Human Umbilical Cord Mesenchymal Stem Cells into Dopaminergic Neuron Containing Cells

Mesenchymal stem cells (MSCs) have the potential to differentiate into neuron-like cells, which may provide a new strategy for the clinical treatment of neurodegenerative diseases such as Parkinson's disease (PD). However, the application of MSCs in the patients is still limited as the reason of efficiency and safety of transplantation. The aim of this study is to develop a new method and induce human umbilical cord MSCs (hUCMSCs) into neuron-like cells. Results from flow cytometry indicate that the isolated MSCs from hUCMSCs exhibited a typical phenotype of adult stem cells and express CD44, CD54, CD73, CD90, CD105, CD166, and HLA-ABC. Furthermore, the induced cells from hUCMSCs could spontaneously express different neural cell markers [neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP)], even transcription factors related to dopaminergic neuron's development (Nurr1, Wnt-1, and En-1). Moreover, after treatment of EHFBT (extracts of human fetal brain tissue), hUCMSCs can express neuronal markers such as Nestin, LIM homeobox transcription factor 1 beta (LMX1B), dopamine beta hydroxylase (DBH), and dopamine transporter (DAT). In summary, a method that can induce hUCMSCs into dopaminergic neuron containing cells is established in vitro by the treatment of EHFBT. This would provide us a new cell source for PD in clinical treatment in the future.

Astragalus saponin IV promotes osteogenic differentiation of bone marrow mesenchymal stem cells via miR-21/NGF/BMP2/Runx2 pathway

BACKGROUND

Astragalus saponin IV(AS- IV) extracted from tranditional Chinese medicine Radix Astragali Mongolici, which had been reported to have medicinal properties in treating several types of diseases. This study aimed at investigating the biological functions of AS-IV on bone marrow mesenchymal cells(BMSCs) differentiation, therefore, seeking for a better application of AS-IV on fracture or other orthopedic disorders.

METHODS

AS-IV was co-incubated with BMSCs in vitro to testify whether it can influence the proliferation and differentiation of BMSCs. Cell proliferation activity was detected by Cell Counting Kit-8 (CCK-8), while its differentiation promoting capibility was obtained by alkaline phosphatase (ALP) activity assay and Alizarin red S staining. Besides, differentiation protein markers of preosteoblast was detected by western blots. Neuron growth factor antagonists (NGFA) and microRNA-21 (miR-21) inhibitors were co incubated with AS-IV to search the regulatory pathways it activated in BMSCs.

RESULTS

AS-IV incubation boosted the proliferation of BMSCs, and accelerated the differentiating direction into preosteoblasts. Runx2, OPN, BMP2, OCN proteins were up regulated after AS- IV treatment. MiR-21/NGF/BMP2/Runx2 pathway can participate the biological effects of AS- IV on BMSCs.

CONCLUSION

AS- IV might be used as a therapeutic agent for bone fracture or other orthopedic disorders.

99mTc-Methyl-Diphosphonate Binding to Mineral Deposits in Cultures of Marrow-Derived Mesenchymal Stem Cells in Osteogenic Medium

IMPACT STATEMENT

The work is notable for describing a highly sensitive, quantitative, and nondestructive method for evaluating the in vitro amount of mineral accompanying different types of osteogenic differentiation of mesenchymal stem cells in a monolayer cell culture. What is so unique and useful about the method is that it has the potential to be used to define the kinetics of the differentiation process, reflected in the mineralization, without destroying the monolayer. Therefore, it remains intact for further experiments.

FOXP1 circular RNA sustains mesenchymal stem cell identity via microRNA inhibition

Stem cell identity and plasticity are controlled by master regulatory genes and complex circuits also involving non-coding RNAs. Circular RNAs (circRNAs) are a class of RNAs generated from protein-coding genes by backsplicing, resulting in stable RNA structures devoid of free 5’ and 3’ ends. Little is known of the mechanisms of action of circRNAs, let alone in stem cell biology. In this study, for the first time, we determined that a circRNA controls mesenchymal stem cell (MSC) identity and differentiation. High-throughput MSC expression profiling from different tissues revealed a large number of expressed circRNAs. Among those, circFOXP1 was enriched in MSCs compared to differentiated mesodermal derivatives. Silencing of circFOXP1 dramatically impaired MSC differentiation in culture and in vivo. Furthermore, we demonstrated a direct interaction between circFOXP1 and miR-17–3p/miR-127–5p, which results in the modulation of non-canonical Wnt and EGFR pathways. Finally, we addressed the interplay between canonical and non-canonical Wnt pathways. Reprogramming to pluripotency of MSCs reduced circFOXP1 and non-canonical Wnt, whereas canonical Wnt was boosted. The opposing effect was observed during generation of MSCs from human pluripotent stem cells. Our results provide unprecedented evidence for a regulatory role for circFOXP1 as a gatekeeper of pivotal stem cell molecular networks.

Mesangiogenic progenitor cells are forced toward the angiogenic fate, in multiple myeloma

Multiple myeloma (MM) progresses mainly in the bone marrow where the involvement of a specific microenvironment plays a critical role in maintaining plasma cell growth, spread, and survival. In active disease, the switch from a pre-vascular/non-active phase to a vascular phase is coupled with the impairment of bone turnover. Previously, we have isolated Mesangiogenic Progenitor Cells (MPCs), a bone marrow population that showed mesengenic and angiogenic potential, both in vitro and in vivo. MPC differentiation into musculoskeletal tissue and their ability of sprouting angiogenesis are mutually exclusive, suggesting a role in the imbalancing of the microenvironment in multiple myeloma.

MPCs from 32 bone marrow samples of multiple myeloma and 23 non-hematological patients were compared in terms of frequency, phenotype, mesengenic/angiogenic potential, and gene expression profile. Defective osteogenesis was recorded for MM-derived MPCs that showed longer angiogenic sprouting distances respect to non-hematological MPCs, retaining this capability after mesengenic induction. This altered MPCs differentiation potential was not detected in asymptomatic myelomatous disease.

These in vitro experiments are suggestive of a forced angiogenic fate in MPCs isolated from MM patients, which also showed increased sprouting activity. Taking together our results suggest a possible role of these cells in the “angiogenic switch” in the MM micro-environment.

Effect of SDF-1 with biphasic ceramic-like bone graft on the repair of rabbit radial defect

BACKGROUND

This study aimed to investigate the effects of stromal cell-derived factor-1 (SDF-1) on biphasic ceramic-like biologic bone (BCBB) in vivo on the repair of large segment bone defect in rabbits.

METHODS

A large-segment radius defect model of the rabbits was constructed. In the experimental group, BCBB with SDF-1 sustained-release system were implanted into the bone defect site. Other three groups including normal control, autologous bone graft, and BCBB implantation without SDF-1 were set. After surgery, general observation, X-ray radiography and scoring, and tissue section staining were performed at 2, 4, 8, 12, and 24 weeks post-implantation.

RESULTS

By general observation, X-ray radiography and grading and tissue section staining observation, we found that the BCBB carrying SDF-1 was better than those in the group of BCBB without SDF-1 (P < 0.05). BCBB scaffold had certain bone conduction capacity, and the BCBB scaffold carrying SDF-1 had improved bone conduction ability and possessed bone induction ability. In the case of carrying SDF-1, it can be used to repair large bone defects in a shorter time than simply using BCBB, which is equivalent to the effect of autologous bone.

CONCLUSION

BCBB scaffold carrying SDF-1 can promote the repair effect on a large bone defect, which is equivalent to the effect of autologous bone.

Peripheral artery disease: the new frontiers of imaging techniques to evaluate the evolution of regenerative medicine

Introduction: Stem cells (ESC, iPSC, MSC) are known to have intrinsic regenerative properties. In the last decades numerous findings have favored the development of innovative therapeutic protocols based on the use of stem cells (Regenerative Medicine/Cell Therapy) for the treatment of numerous diseases including PAD, with promising results in preclinical studies. So far, several clinical studies have shown a general improvement of the patient's clinical outcome, however they possess many critical issues caused by the non-randomized design of the limited number of patients examined, the type cells to be used, their dosage, the short duration of treatment and also their delivery strategy. Areas covered: In this context, the use of the most advanced molecular imaging techniques will allow the visualization of very important physio-pathological processes otherwise invisible with conventional techniques, such as angiogenesis, also providing important structural and functional data. Expert opinion: The new frontier of cell therapy applied to PAD, potentially able to stop or even the process that causes the disease, with particular emphasis on the clinical aspects that different types of cells involve and on the use of more innovative molecular imaging techniques now available.

Peroxiredoxin 6 Inhibits Osteogenic Differentiation and Bone Formation Through Human Dental Pulp Stem Cells and Induces Delayed Bone Development

Aims: Peroxiredoxins (PRDXs) are thiol-specific antioxidant enzymes that regulate redox balance that are critical for maintaining the cellular potential for self-renewal and stemness. Stem cell-based regenerative medicine is a promising approach in tissue reconstruction. However, to obtain functional cells for use in clinical applications, stem cell technology still requires improvements. Results: In this study, we found that PRDX6 levels were decreased during osteogenic differentiation in human dental pulp stem cells (hDPSCs). hDPSCs stably expressing Myc-PRDX6 (hDPSC/myc-PRDX6) inhibited cell growth in hDPSCs during osteogenic differentiation and impaired osteogenic phenotypes such as alkaline phosphatase (ALP) activity, mineralized nodule formation, and osteogenic marker genes [ALP and osteocalcin (OCN)]. hDPSC cell lines stably expressing mutant glutathione peroxidase (PRDX6(C47S)) and independent phospholipase A2 (PRDX6(S32A)) were also generated. Each mutant form of PRDX6 abolished the impaired osteogenic phenotypes, the transforming growth factor-β-mediated Smad2 and p38 pathways, and RUNX2 expression. Furthermore, in vivo experiments revealed that hDPSC/myc-PRDX6 suppressed hDPSC-based bone regeneration in calvarial defect mice, and newborn PRDX6 transgenic mice exhibited delayed bone development and reduced RUNX2 expression. Innovation and Conclusion: These findings illuminate the effects of PRDX6 during osteogenic differentiation of hDPSCs, and also suggest that regulating PRDX6 may improve the clinical utility of stem cell-based regenerative medicine for the treatment of bone diseases. Antioxid. Redox Signal. 30, 1969-1982.

Self-Assembled Injectable Nanocomposite Hydrogels Coordinated by in Situ Generated CaP Nanoparticles for Bone Regeneration

Due to the great similarity to the natural extracellular matrix and minimally invasive surgeries, injectable hydrogels are appealing biomaterials in cartilage and bone tissue engineering. Nevertheless, undesirable mechanical properties and bioactivity greatly hamper their availability in clinic applications. Here, we developed an injectable nanocomposite hydrogel by in situ growth of CaP nanoparticles (ICPNs) during the free-radical polymerization of dimethylaminoethyl methacrylate (DMAEMA) and 2-hydroxyethyl methacrylate (HEMA) matrix (PDH) for bone regeneration. The ICPNs are self-assembled by incorporation of poly-l-glutamic acid (PGA) with abundant carboxyl functional groups during the formation of carboxyl-Ca²⁺ coordination and further CaP precipitation. Furthermore, the carboxyl groups of PGA could interact with the tertiary amines of DMAEMA fragments and thus improve the mechanical strength of hydrogels. Upon mixing solutions of DMAEMA and HEMA bearing PGA, Ca²⁺, and PO₄^3-, this effective and dynamic coordination led to the rapid self-assembly of CaP NPs and PDH nanocomposite hydrogels (PDH/mICPN). The obtained optimal nanocomposite hydrogels exhibited suitable injectable time, an enhanced tensile strength of 321.1 kPa, and a fracture energy of 29.0 kJ/m² and dramatically facilitated cell adhesion and upregulated osteodifferentiation compared to hydrogels prepared by blending ex situ prefabricated CaP NPs. In vivo experiments confirmed the promoted osteogenesis, which shows a striking contrast to pure PDH hydrogels. Additionally, the methacrylate groups on the monomers could easily be functionalized with aptamers and thereby facilitate recognition and capturing of bone marrow stromal cells both in vitro and in vivo and strengthen the bone regeneration. We believe that our conducted research about in situ self-assembled CaP nanoparticle-coordinated hydrogels will open a new avenue for bone regeneration in the future endeavors.

Emergent heterogeneity in putative mesenchymal stem cell colonies: Single-cell time lapsed analysis

Bone marrow stromal cells (BMSCs) include a subset of stem cells that are considered promising for developmental studies and therapeutic applications. While it is appreciated generally that BMSC populations can exhibit morphological and functional heterogeneity upon in vitro culture expansion, the potential for heterogeneity within a single colony forming unit–generated ostensibly from a single mother cell–is less explored but is critical to design of both fundamental studies and cell therapy production. Here we observed BMSC colony formation in real time via time lapsed optical imaging and analysis, to quantify whether and how heterogeneity emerged over multiple cell divisions spanning the duration of a typical colony formation unit assay. These analyses demonstrate that such colonies are neither homogeneous subpopulations of stem cells nor necessarily derived from single originating cells. While the mechanisms for and causes of this intracolony heterogeneity are not understood fully, we further demonstrate that extensive cell-cell contacts do not correlate with senescence, but that media exchange was concurrent with diversification in even the most uniform single-cell-derived colonies. These direct quantitative observations and visualizations of colony formation provide new insights that are motivated by significant implications for both basic research and stem cell-based therapies.

Tissue engineered bone mimetics to study bone disorders ex vivo: Role of bioinspired materials

Recent advances in materials development and tissue engineering has resulted in a substantial number of bioinspired materials that recapitulate cardinal features of bone extracellular matrix (ECM) such as dynamic inorganic and organic environment(s), hierarchical organization, and topographical features. Bone mimicking materials, as defined by its self-explanatory term, are developed based on the current understandings of the natural bone ECM during development, remodeling, and fracture repair. Compared to conventional plastic cultures, biomaterials that resemble some aspects of the native environment could elicit a more natural molecular and cellular response relevant to the bone tissue. Although current bioinspired materials are mainly developed to assist tissue repair or engineer bone tissues, such materials could nevertheless be applied to model various skeletal diseases in vitro. This review summarizes the use of bioinspired materials for bone tissue engineering, and their potential to model diseases of bone development and remodeling ex vivo. We largely focus on biomaterials, designed to re-create different aspects of the chemical and physical cues of native bone ECM. Employing these bone-inspired materials and tissue engineered bone surrogates to study bone diseases has tremendous potential and will provide a closer portrayal of disease progression and maintenance, both at the cellular and tissue level. We also briefly touch upon the application of patient-derived stem cells and introduce emerging technologies such as organ-on-chip in disease modeling. Faithful recapitulation of disease pathologies will not only offer novel insights into diseases, but also lead to enabling technologies for drug discovery and new approaches for cell-based therapies.

A mouse model for the study of transplanted bone marrow mesenchymal stem cell survival and proliferation in lumbar spinal fusion

PURPOSE

Bone marrow aspirate has been successfully used alongside a variety of grafting materials to clinically augment spinal fusion. However, little is known about the fate of these transplanted cells. Herein, we develop a novel murine model for the in vivo monitoring of implanted bone marrow cells (BMCs) following spinal fusion.

METHODS

A clinical-grade scaffold was implanted into immune-intact mice undergoing spinal fusion with or without freshly isolated BMCs from either transgenic mice which constitutively express the firefly luciferase gene or syngeneic controls. The in vivo survival, distribution and proliferation of these luciferase-expressing cells was monitored via bioluminescence imaging over a period of 8 weeks and confirmed via immunohistochemistry. MicroCT imaging was performed 8 weeks to assess fusion.

RESULTS

Bioluminescence imaging indicated transplanted cell survival and proliferation over the first 2 weeks, followed by a decrease in cell numbers, with transplanted cell survival still evident at the end of the study. New bone formation and increased fusion mass volume were observed in mice implanted with cell-seeded scaffolds.

CONCLUSIONS

By enabling the tracking of transplanted bone marrow-derived cells during spinal fusion in vivo, this mouse model will be integral to developing a deeper understanding of the biological processes underlying spinal fusion in future studies. These slides can be retrieved under Electronic Supplementary Material.

HDAC6 regulates dental mesenchymal stem cells and osteoclast differentiation

Background

Dental and periodontal tissue development is a complicated process involving a finely regulated network of communication among various cell types. Understanding the mechanisms involved in regulating dental mesenchymal stem cells (MSCs) and osteoclast cell differentiation is critical. However, it is still unclear whether histone deacetylase HDAC6 is involved in dental MSCs fate determination and osteoclast differentiation.

Methods

We used shRNA and siRNA knockdown to explore the role of HDAC6 in dental MSCs odontogenic differentiation and osteoclasts maturation.

Results

Based on HDAC6 knockdown dental MSCs, our data suggest that HDAC6 knockdown significantly increases alkaline phosphate activity and mineralized nodules formation. Additionally, mRNA expression of odontogenic marker genes (OSX, OCN, and OPN) was induced by HDAC6 knockdown. By using HDAC6 siRNA, we knocked down HDAC6 in osteoclast precursor RAW 264.7 cells. Our data suggests that HDAC6 knockdown significantly inhibited osteoclasts differentiation. Additionally, mRNA expression of osteoclast marker genes Trap, Mmp9, and Ctsk was decreased by HDAC6 knockdown.

Conclusions

Our study demonstrated that HDAC6 plays an important role in regulating dental MSCs and osteoclasts differentiation.

Application of mesenchymal stem cells to enhance non-union bone fracture healing

ECM components include a number of osteoinductive and osteoconductive factors, which are involved in bone fracture healing. In this study, a combination of adipose derived mesenchymal stem cells (Ad-MSCs), cancellous bone graft (CBG), and chitosan hydrogel (CHI) was applied to the non-union bone fracture and healing effects were evaluated for the first time. After creation of animal models with non-union fracture in rats, they were randomly classified into seven groups. Radiography at 0, 2, 4, and 8 weeks after surgery, indicated the positive effects of Ad-MSCs + CBG + CHI and Ad-MSCs + CBG in treatment of bone fractures as early as 2 weeks after the surgery. These data were confirmed with both biomechanical and histological studies. Gene expression analyses of Vegf and Bmp2 showed a positive effect of Ad-MSCs on vascularization and osteogenic differentiation in all groups receiving Ad-MSCs, as shown by real-time PCR. Immunofluorescence analysis and RT-PCR results indicated existence of human Ad-MSCs in the fractured region 8 weeks post-surgery. In conclusion, we suggest that application of Ad-MSCs, CBG, and CHI, could be a suitable combination for osteoinduction and osteoconduction to improve non-union bone fracture healing. Further investigations are required to determine the exact mechanisms involved in this process before moving to clinical studies. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 301-311, 2019.

MicroRNA-29a-3p enhances dental implant osseointegration of hyperlipidemic rats via suppressing dishevelled 2 and frizzled 4

Background

Fine osseointegration is the basis of long-term survival of implant. In our previous study, we observed a strong correlation between hyperlipidemia and compromised osseointegration. MicroRNA-29a-3p (miR-29a-3p) has been discovered to participate in bone marrow mesenchymal stem cells (BMSCs) differentiation. However, the role and the underlying mechanisms of hyperlipidemia and miR-29a-3p in osseointegration still remain obscure.

Results

In peri-implant bone tissues of hyperlipidemia rats, bone mass, mineralization and bone trabecula formation were weakened. Alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2), and miR-29a-3p expression were reduced. While in normal rats, implant-bone interfaces were filled with dense new bone and ALP, Runx2 and miR-29a-3p were up-regulated. Overexpressed miR-29a-3p can reverse the adverse effect of hyperlipidemia on osseointegration. Implants were tightly integrated with the surrounding dense new bone tissues, and ALP as well as Runx2 mRNAs were enhanced in miR-29a-3p overexpressed and hyperlipidemia rats, while little peri-implant bone tissue existed, ALP and Runx2 deregulated on miR-29a-3p inhibited rats. Dishevelled 2 (Dvl2) mRNA was declined in peri-implant bone tissue of high-fat (HF) group than normal group, while frizzled 4 (Fzd4) mRNA declined on day 5 and increased from day 10 to day 20 after implantation in hyperlipidemia rats than in normal rats. Next, BMSCs were cultured under HF or normal medium in vitro. In the HF group, ALP activity and mineralization, ALP and Runx2 mRNAs and proteins expression, and miR-29a-3p expression were suppressed, while adipogenesis was increased, as a result, cytoskeletons were sparse and disordered compared to control group. However, when miR-29a-3p was overexpressed in BMSCs, ALP activity, ALP, Runx2, Dvl2 and Fzd4 mRNAs and proteins expressions were up-regulated. As miR-29a-3p was inhibited in BMSCs, the reverse results were obtained. In addition, promoter assay revealed that miR-29a-3p can directly suppress Wnt/β-catenin pathway related Dvl2 and Fzd4 through binding to their 3'-UTR.

Conclusions

MiR-29a-3p facilitated implant osseointegration via targeting Wnt/β-catenin pathway-related Dvl2 and Fzd4. MiR-29a-3p/Dvl2/Fzd4 may serve as a promising therapeutic target for hyperlipidemia osseointegration.

Bone regeneration with umbilical cord blood mesenchymal stem cells in femoral defects of ovariectomized rats

OBJECTIVES

Current treatments for osteoporosis were prevention of progression, yet it has been questionable in the stimulation of bone growth. The mesenchymal stem cells (MSCs) treatment for osteoporosis aims to induce differentiation of bone progenitor cells into bone-forming osteoblasts. We investigate whether human umbilical cord blood (hUCB)-MSCs transplantation may induce bone regeneration for osteoporotic rat model induced by ovariectomy.

METHODS

The ovariectomized (OVX) group (n = 10) and OVX-MSCs group (n = 10) underwent bilateral ovariectomy to induce osteoporosis, while the Sham group (n = 10) underwent sham operation at aged 12 weeks. After a femoral defect was made at 9 months, Sham group and OVX group were injected with Hartmann solution, while the OVX-MSCs group was injected with Hartmann solution containing 1 × 107 hUCB-MSCs. The volume of regenerated bone was evaluated using micro-computed tomography at 4 and 8 weeks postoperation.

RESULTS

At 4- and 8-week postoperation, the OVX group (5.0% ± 1.5%; 6.1% ± 0.7%) had a significantly lower regenerated bone volume than the Sham group (8.6% ± 1.3%; 12.0% ± 1.8%, P < 0.01), respectively. However, there was no significant difference between the OVX-MSCs and Sham groups. The OVX-MSCs group resulted in about 53% and 65% significantly higher new bone formation than the OVX group (7.7% ± 1.9%; 10.0% ± 2.9%, P < 0.05).

CONCLUSIONS

hUCB-MSCs in bone defects may enhance bone regeneration in osteoporotic rat model similar to nonosteoporotic bone regeneration. hUCB-MSCs may be a promising alternative stem cell therapy for osteoporosis.

The impact of photofunctionalized gold nanoparticles on osseointegration

OBJECTIVES

The aims of this study were to create a new surface topography using simulated body fluids (SBF) and Gold Nanoparticles (GNPs) and then to assess the influence of UV Photofunctionalization (PhF) on the osteogenic capacity of these surfaces.

MATERIALS AND METHODS

Titanium plates were divided into six groups All were acid etched with 67% Sulfuric acid, 4 were immersed in SBF and 2 of these were treated with 10 nm GNPs. Half of the TiO2 plates were photofunctionalized to be compared with the non-PhF ones. Rat's bone marrow stem cells were seeded into the plates and then CCK8 assay, cell viability assay, immunofluorescence, and Scanning electron microscopy (SEM) were done after 24 hours. Gene expression analysis was done using real time quantitative PCR (qPCR) one week later to check for the mRNA expression of Collagen-1, Osteopontin and Osteocalcin. Alkaline phosphatase (ALP) activity was assessed after 2 weeks of cell seeding.

RESULTS

Our new topography has shown remarkable osteogenic potential. The new surface was the most biocompatible, and the 10 nm GNPs did not show any cytotoxicity. There was a significant increase in bioactivity, enhanced gene expressions and ALP activity.

CONCLUSIONS

GNPs enhances osteogenic differentiation of stem cells and Photofunctionalizing GNPs highly increases this. We have further created a novel highly efficient topography which highly enhances the speed and extent of osseointegration. This may have great potential for improving treatment outcomes for implant, maxillofacial as well as orthopedic patients.

Efficient in vitro delivery of Noggin siRNA enhances osteoblastogenesis

Several types of serious bone defects would not heal without invasive clinical intervention. One approach to such defects is to enhance the capacity of bone-formation cells. Exogenous bone morphogenetic proteins (BMP) have been utilized to positively regulate matrix mineralization and osteoblastogenesis, however, numerous adverse effects are associated with this approach. Noggin, a potent antagonist of BMPs, is an ideal candidate to target and decrease the need for supraphysiological doses of BMPs. In the current research we report a novel siRNA-mediated gene knock-down strategy to down-regulate Noggin. We utilized a lipid nanoparticle (LNP) delivery strategy in pre-osteoblastic rat cells. In vitro LNP-siRNA treatment caused inconsequential cell toxicity and transfection was achieved in over 85% of cells. Noggin siRNA treatment successfully down-regulated cellular Noggin protein levels and enhanced BMP signal activity which in turn resulted in significantly increased osteoblast differentiation and extracellular matrix mineralization evidenced by histological assessments. Gene expression analysis showed that targeting Noggin specifically in bone cells would not lead to a compensatory effect from other BMP negative regulators such as Gremlin and Chordin. The results from this study support the notion that novel therapeutics targeting Noggin have the clinically relevant potential to enhance bone formation without the need for toxic doses of exogenous BMPs. Such treatments will undeniably provide safe and economical treatments for individuals whose poor bone repair results in permanent morbidity and disability.

Transplantation of human skeletal muscle-derived progenitor cells ameliorates knee osteoarthritis in streptozotocin-induced diabetic mice

The epidemiological and experimental evidence suggests that diabetes can be an independent risk factor for osteoarthritis. The osteoarthritis-like cartilage damage has been shown in streptozotocin-induced diabetic mice. The therapeutic effects of human skeletal muscle-derived progenitor cells (HSMPCs) on diabetic osteoarthritis still remain unclear. Here, we investigated the therapeutic potential of HSMPCs on diabetic knee osteoarthritis. The in vitro chondrogenic ability of HSMPCs was determined by pellet culture assay. Male mice were used to develop the model of streptozotocin-induced type 1 diabetes and its related osteoarthritis. HSMPCs were injected intra-articularly to rescue osteoarthritis. Protein expressions of advanced glycation end-products, cyclooxygenase-2, and type-2 collagen in tissues were determined by immunohistochemistry. The pellet culture assay showed that HSMPCs cultured in differentiation medium for chondrogenesis significantly produced larger pellets with an overproduction of extracellular matrix than in growth medium. In in vivo experiments, intra-articular injection of HSMPCs for 4 weeks significantly prevented the progression of degenerative changes in the cartilage of streptozotocin-induced diabetic mice, including an obvious increase of total articular cartilage thickness and a decrease of fibrous cartilage thickness. HSMPCs transplantation also exerted the decline in advanced glycation end-products and cyclooxygenase-2 protein expression, but increased the type-2 collagen protein expression in streptozotocin-induced osteoarthritic cartilages. Moreover, HSMPCs transplantation also inhibited the increased serum interleukin-6 and matrix metalloproteinase-3 levels in diabetic mice. These results demonstrated for the first time that HSMPCs transplantation ameliorates cartilage degeneration in diabetes-related osteoarthritis mice. These findings suggest that HSMPCs transplantation may apply as a potential therapeutic use of diabetes-related osteoarthritis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1886-1893, 2017.

Bone Regenerative Medicine in Oral and Maxillofacial Region Using a Three-Dimensional Printer<sup/>

Bone grafts currently used for the treatment of large bone defect or asymmetry in oral and maxillofacial region include autologous, allogeneic, and artificial bones. Although artificial bone is free from the concerns of donor site morbidity, limitation of volume, disease transmission, and ethical issues, it lacks osteogenic and osteoinductive activities. In addition, molding of the artificial bone is an issue especially when it is used for the augmentation of bone as onlay grafts. To solve this problem, additive manufacturing techniques have been applied to fabricate bones which have outer shapes conformed to patients' bones. We developed a custom-made artificial bone called a computed tomography (CT)-bone. Efficacy of CT-bone was proven in a clinical research and clinical trial, showing good manipulability, stability, and patient satisfaction. However, low replacement rate of artificial bones by endogenous bones remain an unsolved issue. Loading of cells and growth factors will improve the bone replacement by inducing osteogenic and osteoinductive activities. In addition, the three-dimensional bioprinting technique will facilitate bone regeneration by placing cells and biological substances into appropriate sites.

Distribution pattern following systemic mesenchymal stem cell injection depends on the age of the recipient and neuronal health

Background

Mesenchymal stem cells (MSCs) show therapeutic efficacy in many different age-related degenerative diseases, including Alzheimer’s disease. Very little is currently known about whether or not aging impacts the transplantation efficiency of MSCs.

Methods

In this study, we investigated the distribution of intravenously transplanted syngeneic MSCs derived from young and aged mice into young, aged, and transgenic APP/PS1 Alzheimer’s disease mice. MSCs from male donors were transplanted into female mice and their distribution pattern was monitored by PCR using Y-chromosome specific probes. Biodistribution of transplanted MSCs in the brains of APP/PS1 mice was additionally confirmed by immunofluorescence and confocal microscopy.

Results

Four weeks after transplantation into young mice, young MSCs were found in the lung, axillary lymph nodes, blood, kidney, bone marrow, spleen, liver, heart, and brain cortex. In contrast, young MSCs that were transplanted into aged mice were only found in the brain cortex. In both young and aged mouse recipients, transplantation of aged MSCs showed biodistribution only in the blood and spleen. Although young transplanted MSCs only showed neuronal distribution in the brain cortex in young mice, they exhibited a wide neuronal distribution pattern in the brains of APP/PS1 mice and were found in the cortex, cerebellum, hippocampus, olfactory bulb, and brainstem. The immunofluorescent signal of both transplanted MSCs and resident microglia was robust in the brains of APP/PS1 mice. Monocyte chemoattractant-1 levels were lowest in the brain cortex of young mice and were significantly increased in APP/PS1 mice. Within the hippocampus, monocyte chemoattractant-1 levels were significantly higher in aged mice compared with younger and APP/PS1 mice.

Conclusions

We demonstrate in vivo that MSC biodistribution post transplantation is detrimentally affected by aging and neuronal health. Aging of both the recipient and the donor MSCs used attenuates transplantation efficiency. Clinically, our data would suggest that aged MSCs should not be used for transplantation and that transplantation of MSCs into aged patients will be less efficacious.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0533-2) contains supplementary material, which is available to authorized users.