Preclinical Studies of the Biosafety and Efficacy of Human Bone Marrow Mesenchymal Stem Cells Pre-Seeded into β-TCP Scaffolds after Transplantation

Materials in the Na2O-CaO-SiO2-P2O5 System for Medical Applications

Calcium phosphate materials and materials based on silicon dioxide have been actively studied for more than 50 years due to their high biocompatibility and bioactivity. Hydroxyapatite and tricalcium phosphate are the most known among calcium phosphate materials, and Bioglass 45S5 is the most known material in the Na2O-CaO-SiO2-P2O5 system. Each of these materials has its application limits; however, some of them can be eliminated by obtaining composites based on calcium phosphate and bioglass. In this article, we provide an overview of the role of silicon and its compounds, including Bioglass 45S5, consider calcium phosphate materials, talk about the limits of each material, demonstrate the potential of the composites based on them, and show the other ways of obtaining composite ceramics in the Na2O-CaO-SiO2-P2O5 system.

Preclinical Short-term and Long-term Safety of Human Bone Marrow Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have become a promising therapeutic method. More safety data are needed to support clinical studies in more diseases. The aim of this study was to investigate the short- and long-term safety of human bone marrow-derived MSCs (hBMMSCs) in mice. In the present study, we injected control (saline infusion only), low (1.0 × 106/kg), medium (1.0 × 107/kg), and high (1.0 × 108/kg) concentrations of hBMMSCs into BALB/c mice. The safety of the treatment was evaluated by observing changes in the general condition, hematology, biochemical indices, pathology of vital organs, lymphocyte subsets, and immune factor levels on days 14 and 150. In the short-term toxicity test, no significant abnormalities were observed in the hematological and biochemical parameters between the groups injected with hBMMSCs, and no significant damage was observed in the major organs, such as the liver and lung. In addition, no significant differences were observed in the toxicity-related parameters among the groups in the long-term toxicity test. Our study also demonstrates that mice infused with different doses of hBMMSCs do not show abnormal immune responses in either short-term or long-term experiments. We confirmed that hBMMSCs are safe through a 150-day study, demonstrating that this is a safe and promising therapy and offering preliminary safety evidence to promote future clinical applications of hBMMSCs in different diseases.

Dexamethasone and Doxycycline Doped Nanoparticles Increase the Differentiation Potential of Human Bone Marrow Stem Cells

Non-resorbable polymeric nanoparticles (NPs) are proposed as an adjunctive treatment for bone regenerative strategies. The present in vitro investigation aimed to evaluate the effect of the different prototypes of bioactive NPs loaded with zinc (Zn-NPs), doxycycline (Dox-NPs) or dexamethasone (Dex-NPs) on the viability, morphology, migration, adhesion, osteoblastic differentiation, and mineralization potential of human bone marrow stem cells (hBMMSCs). Cell viability, proliferation, and differentiation were assessed using a resaruzin-based assay, cell cycle analysis, cell migration evaluation, cell cytoskeleton staining analysis, Alizarin Red S staining, and expression of the osteogenic-related genes by a real-time quantitative polymerase chain reaction (RT-qPCR). One-Way ANOVA and Tukey’s test were employed. The resazurin assay showed adequate cell viability considering all concentrations and types of NPs at 24, 48, and 72 h of culture. The cell cycle analysis revealed a regular cell cycle profile at 0.1, 1, and 10 µg/mL, whereas 100 µg/mL produced an arrest of cells in the S phase. Cells cultured with 0.1 and 1 µg/mL NP concentrations showed a similar migration capacity to the untreated group. After 21 days, mineralization was increased by all the NPs prototypes. Dox-NPs and Dex-NPs produced a generalized up-regulation of the osteogenic-related genes. Dex-NPs and Dox-NPs exhibited excellent osteogenic potential and promoted hBMMSC differentiation. Future investigations, both in vitro and in vivo, are required to confirm the suitability of these NPs for their clinical application.

Standard toxicity study of clinical-grade allogeneic human bone marrow-derived clonal mesenchymal stromal cells

INTRODUCTION

Mesenchymal stromal cells (MSCs) have opened a new window to treat inflammatory and non-inflammatory diseases. Nonetheless, their clinical applications require rigorous control and monitoring procedures to ensure full compliance with the principles of good manufacturing practice (GMP). Various evaluations should be passed in conjunction with the development of these newly emerging therapeutic products from bench-to-bedside. These evaluations include in vitro characterization, preclinical studies, and clinical trials to ensure product safety and efficacy. Therefore, a robust and well-designed preclinical study is critical to confirm product safety. This study aims to determine the probable toxicity effects of local and systemic injections of cryopreserved human bone marrow-derived clonal MSCs (BM-cMSCs) during subacute and subchronic periods of time.

METHODS

BM-cMSCs were characterized according to the International Society for Cell and Gene Therapy (ISCT) criteria for MSCs. Both safety and toxicity of the BM-cMSCs population produced under GMP-compatible conditions were assessed in both sexes of Sprague Dawley (SD) rats via systemic intravenous (IV) administration and local injection in intervertebral disc (IVD). Behavioral changes, clinical signs of toxicity, and changes in body weight, water and food consumption were the important variables for product toxicity testing over 14 consecutive days during the subacute period and 90 consecutive days during the subchronic period. At the end of the assessment periods, the rats were killed for histopathology analysis of the target tissues. The BM-cMSCs potential for tumorigenicity was checked in nude mice.

RESULTS

Single IV and IVD injections of BM-cMSCs did not cause significant signs of clinical toxicity, or changes in laboratory and histopathology data during the subacute (14 day) and subchronic (90 day) periods. Ex vivo-expanded and cryopreserved BM-cMSCs did not induce tumor formation in nude mice.

CONCLUSION

The results suggest that local and systemic administrations of xenogeneic BM-cMSCs in both sexes of SD rats do not cause toxicity during the subacute and subchronic periods of time. Also, BM-cMSCs were non-tumorigenic in nude mice.

Preclinical Safety Evaluation of Intranasally Delivered Human Mesenchymal Stem Cells in Juvenile Mice

Simple Summary

The concept of utilizing mesenchymal stem cells for the treatment of central nervous system disorders has progressed from preclinical studies to clinical trials. While promising, the effectiveness of cell therapy is hampered by the route used to deliver cells into the brain. In this context, intranasal cell administration has boomed over the past few years as an effective cell delivery method. However, comprehensive safety studies are required before translation to the clinic. Our study shed light on how intranasally administrated mesenchymal stem cells may be used to safely treat neurological disorders.

Abstract

Mesenchymal stem cell (MSC)-based therapy is a promising therapeutic approach in the management of several pathologies, including central nervous system diseases. Previously, we demonstrated the therapeutic potential of human adipose-derived MSCs for neurological sequelae of oncological radiotherapy using the intranasal route as a non-invasive delivery method. However, a comprehensive investigation of the safety of intranasal MSC treatment should be performed before clinical applications. Here, we cultured human MSCs in compliance with quality control standards and administrated repeated doses of cells into the nostrils of juvenile immunodeficient mice, mimicking the design of a subsequent clinical trial. Short- and long-term effects of cell administration were evaluated by in vivo and ex vivo studies. No serious adverse events were reported on mouse welfare, behavioral performances, and blood plasma analysis. Magnetic resonance study and histological analysis did not reveal tumor formation or other abnormalities in the examined organs of mice receiving MSCs. Biodistribution study reveals a progressive disappearance of transplanted cells that was further supported by an absent expression of human GAPDH gene in the major organs of transplanted mice. Our data indicate that the intranasal application of MSCs is a safe, simple and non-invasive strategy and encourage its use in future clinical trials.

Key components of engineering vascularized 3-dimensional bioprinted bone constructs

Vascularization has a pivotal role in engineering successful tissue constructs. However, it remains a major hurdle of bone tissue engineering, especially in clinical applications for the treatment of large bone defects. Development of vascularized and clinically-relevant engineered bone substitutes with sufficient blood supply capable of maintaining implant viability and supporting subsequent host tissue integration remains a major challenge. Since only cells that are 100-200 µm from blood vessels can receive oxygen through diffusion, engineered constructs that are thicker than 400 µm face a challenging oxygenation problem. Following implantation in vivo, spontaneous ingrowth of capillaries in thick engineered constructs is too slow. Thus, it is critical to provide optimal conditions to support vascularization in engineered bone constructs. To achieve this, an in-depth understanding of the mechanisms of angiogenesis and bone development is required. In addition, it is also important to mimic the physiological milieu of native bone to fabricate more successful vascularized bone constructs. Numerous applications of engineered vascularization with cell-and/or microfabrication-based approaches seek to meet these aims. Three-dimensional (3D) printing promises to create patient-specific bone constructs in the future. In this review, we discuss the major components of fabricating vascularized 3D bioprinted bone constructs, analyze their related challenges, and highlight promising future trends.