Osteoinductive Material to Fine-Tune Paracrine Crosstalk of Mesenchymal Stem Cells With Endothelial Cells and Osteoblasts

Osteoblast-Mesenchymal Stem Cell Coculture Drives In Vitro Osteogenesis in 3D Bioprinted Periosteum

The periosteum serves as a local source of osteoprogenitor cells and vasculature, therefore influencing the key processes of osteogenesis and neovascularization during bone healing. However, it is often not considered in traditional bone tissue engineering strategies. The periosteum consists of two stratified cell layers, including an inner cambium layer, which serves as a local source of osteoblasts (OBs) and osteoprogenitor cells, and an outer fibrous layer, which hosts vasculature, collagen fibers, and support cells. While several studies have investigated different methodologies to produce tissue-engineered periosteum (TEP) substitutes, few have evaluated the roles of specific cell types within the inner cambium layer and their patterning in 3D environments on underlying bone tissue development. Therefore, we sought to investigate whether mesenchymal stem cells (MSCs) alone, OBs alone, or a 1:1 mixture of the two would result in increased osteogenic differentiation of bone layer MSCs in a 3D bioprinted periosteum-bone coculture model in vitro. We first evaluated these effects in a 2D transwell model, demonstrating that OB-containing cultures, either alone or in a mixed population with MSCs, upregulated alkaline phosphatase activity and runt-related transcription factor 2 (RUNX2) expression. In the 3D bioprinted model, the mixed population showed higher levels of RUNX2 expression and calcium deposition, indicating increased osteogenic differentiation within the bone layer. Results obtained from this study provide evidence that a mixed population of MSCs and OBs within the inner cambium layer of TEP can increase bone regeneration.

Impact of Different Cell Types on the Osteogenic Differentiation Process of Mesenchymal Stem Cells

The skeleton is an important organ in the human body. Bone defects caused by trauma, inflammation, tumors, and other reasons can impact the quality of life of patients. Although the skeleton has a certain ability to repair itself, the current most effective method is still autologous bone transplantation due to factors such as blood supply and defect size. Modern medicine is attempting to overcome these limitations through cell therapy, with mesenchymal stem cells (MSCs) playing a crucial role. MSCs can be extracted from different tissues, and their differentiation potential varies depending on the source. Various cells and cell secretions can influence this process. This article, based on previous research, reviews the effects of macrophages, endothelial cells (ECs), nerve cells, periodontal cells, and even some bacteria on MSC osteogenic differentiation, aiming to provide a reference for multicell coculture strategies related to osteogenesis.

General consensus on multimodal functions and validation analysis of perinatal derivatives for regenerative medicine applications

Perinatal tissues, such as placenta and umbilical cord contain a variety of somatic stem cell types, spanning from the largely used hematopoietic stem and progenitor cells to the most recently described broadly multipotent epithelial and stromal cells. As perinatal derivatives (PnD), several of these cell types and related products provide an interesting regenerative potential for a variety of diseases. Within COST SPRINT Action, we continue our review series, revising and summarizing the modalities of action and proposed medical approaches using PnD products: cells, secretome, extracellular vesicles, and decellularized tissues. Focusing on the brain, bone, skeletal muscle, heart, intestinal, liver, and lung pathologies, we discuss the importance of potency testing in validating PnD therapeutics, and critically evaluate the concept of PnD application in the field of tissue regeneration. Hereby we aim to shed light on the actual therapeutic properties of PnD, with an open eye for future clinical application. This review is part of a quadrinomial series on functional/potency assays for validation of PnD, spanning biological functions, such as immunomodulation, anti-microbial/anti-cancer, anti-inflammation, wound healing, angiogenesis, and regeneration.

Hybrid Mineral/Organic Material Induces Bone Bridging and Bone Volume Augmentation in Rat Calvarial Critical Size Defects

In craniofacial bone defects, the promotion of bone volume augmentation remains a challenge. Finding strategies for bone regeneration such as combining resorbable minerals with organic polymers would contribute to solving the bone volume roadblock. Here, dicalcium phosphate dihydrate, chitosan and hyaluronic acid were used to functionalize a bone-side collagen membrane. Despite an increase in the release of inflammatory mediators by human circulating monocytes, the in vivo implantation of the functionalized membrane allowed the repair of a critical-sized defect in a calvaria rat model with de novo bone exhibiting physiological matrix composition and structural organization. Microtomography, histological and Raman analysis combined with nanoindentation testing revealed an increase in bone volume in the presence of the functionalized membrane and the formation of woven bone after eight weeks of implantation; these data showed the potential of dicalcium phosphate dihydrate, chitosan and hyaluronic acid to induce an efficient repair of critical-sized bone defects and establish the importance of thorough multi-scale characterization in assessing biomaterial outcomes in animal models.

Antibacterial and Immunomodulatory Properties of Acellular Wharton’s Jelly Matrix

Of all biologic matrices, decellularized tissues have emerged as a promising tool in the field of regenerative medicine. Few empirical clinical studies have shown that Wharton’s jelly (WJ) of the human umbilical cord promotes wound closure and reduces wound-related infections. In this scope, we herein investigated whether decellularized (DC)-WJ could be used as an engineered biomaterial. In comparison with devitalized (DV)-WJ, our results showed an inherent effect of DC-WJ on Gram positive (S. aureus and S. epidermidis) and Gram negative (E. coli and P. aeruginosa) growth and adhesion. Although DC-WJ activated the neutrophils and monocytes in a comparable magnitude to DV-WJ, macrophages modulated their phenotypes and polarization states from the resting M0 phenotype to the hybrid M1/M2 phenotype in the presence of DC-WJ. M1 phenotype was predominant in the presence of DV-WJ. Finally, the subcutaneous implantation of DC-WJ showed total resorption after three weeks of implantation without any sign of foreign body reaction. These significant data shed light on the potential regenerative application of DC-WJ in providing a suitable biomaterial for tissue regenerative medicine and an ideal strategy to prevent wound-associated infections.

Nanostructured Modifications of Titanium Surfaces Improve Vascular Regenerative Properties of Exosomes Derived from Mesenchymal Stem Cells: Preliminary In Vitro Results

(1) Background: Implantation of metal-based scaffolds is a common procedure for treating several diseases. However, the success of the long-term application is limited by an insufficient endothelialization of the material surface. Nanostructured modifications of metal scaffolds represent a promising approach to faster biomaterial osteointegration through increasing of endothelial commitment of the mesenchymal stem cells (MSC). (2) Methods: Three different nanotubular Ti surfaces (TNs manufactured by electrochemical anodization with diameters of 25, 80, or 140 nm) were seeded with human MSCs (hMSCs) and their exosomes were isolated and tested with human umbilical vein endothelial cells (HUVECs) to assess whether TNs can influence the secretory functions of hMSCs and whether these in turn affect endothelial and osteogenic cell activities in vitro. (3) Results: The hMSCs adhered on all TNs and significantly expressed angiogenic-related factors after 7 days of culture when compared to untreated Ti substrates. Nanomodifications of Ti surfaces significantly improved the release of hMSCs exosomes, having dimensions below 100 nm and expressing CD63 and CD81 surface markers. These hMSC-derived exosomes were efficiently internalized by HUVECs, promoting their migration and differentiation. In addition, they selectively released a panel of miRNAs directly or indirectly related to angiogenesis. (4) Conclusions: Preconditioning of hMSCs on TNs induced elevated exosomes secretion that stimulated in vitro endothelial and cell activity, which might improve in vivo angiogenesis, supporting faster scaffold integration.

Recent Progresses in the Treatment of Osteoporosis

Osteoporosis (OP) is a chronic bone disease characterized by aberrant microstructure and macrostructure of bone, leading to reduced bone mass and increased risk of fragile fractures. Anti-resorptive drugs, especially, bisphosphonates, are currently the treatment of choice in most developing countries. However, they do have limitations and adverse effects, which, to some extent, helped the development of anabolic drugs such as teriparatide and romosozumab. In patients with high or very high risk for fracture, sequential or combined therapies may be considered with the initial drugs being anabolic agents. Great endeavors have been made to find next generation drugs with maximal efficacy and minimal toxicity, and improved understanding of the role of different signaling pathways and their crosstalk in the pathogenesis of OP may help achieve this goal. Our review focused on recent progress with regards to the drug development by modification of Wnt pathway, while other pathways/molecules were also discussed briefly. In addition, new observations made in recent years in bone biology were summarized and discussed for the treatment of OP.

Intravitreal autologous mesenchymal stem cell transplantation: a non-randomized phase I clinical trial in patients with retinitis pigmentosa

Background

Retinitis pigmentosa (RP) is a progressive inherited retinal disease with great interest for finding effective treatment modalities. Stem cell-based therapy is one of the promising candidates. We aimed to investigate the safety, feasibility, and short-term efficacy of intravitreal injection of bone marrow-derived mesenchymal stem cells (BM-MSCs) in participants with advanced stage RP.

Methods

This non-randomized phase I clinical trial enrolled 14 participants, categorized into three groups based on a single dose intravitreal BM-MSC injection of 1 × 10⁶, 5 × 10⁶, or 1 × 10⁷ cells. We evaluated signs of inflammation and other adverse events (AEs). We also assessed the best corrected visual acuity (BCVA), visual field (VF), central subfield thickness (CST), and subjective experiences.

Results

During the 12-month period, we noticed several mild and transient AEs. Interestingly, we found statistically significant improvements in the BCVA compared to baseline, although they returned to the baseline at 12 months. The VF and CST were stable, indicating no remarkable disease progression. We followed 12 participants beyond the study period, ranging from 1.5 to 7 years, and observed one severe but manageable AE at year 3.

Conclusion

Intravitreal injection of BM-MSCs appears to be safe and potentially effective. All adverse events during the 12-month period required observation without any intervention. For the long-term follow-up, only one participant needed surgical treatment for a serious adverse event and the vision was restored. An enrollment of larger number of participants with less advanced RP and long-term follow-up is required to evaluate the safety and efficacy of this intervention.

Trial registration

ClinicalTrials.gov, NCT01531348. Registered on February 10, 2012

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-020-02122-7.

Biopolymers-calcium phosphate antibacterial coating reduces the pathogenicity of internalized bacteria by mesenchymal stromal cells

A multifunctional material system that kills bacteria and drives bone healing is urgently sought to improve bone prosthesis. Herein, the osteoinductive coating made of calcium phosphate/chitosan/hyaluronic acid, named Hybrid, was proposed as an antibacterial substrate for stromal cell adhesion. This Hybrid coating possesses a contact-killing effect reducing by 90% the viability of Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa) strains after 48 h of contact. In addition to the production of immunomodulatory mediators, Wharton's jelly (WJ-SCs), dental pulp (DPSCs) and bone marrow (BM-MSCs) derived stromal cells were able to release antibacterial and antibiofilm agents effective against S. aureus and P. aeruginosa strains, respectively. Studying the effect of the Hybrid coating on the internalization of S. aureus by the stromal cells, in acute-mimicking bone infection, highlighted an increase in the bacteria internalization by DPSCs and BM-MSCs when cultured on the Hybrid coating versus uncoated glass. Despite the internalization, Hybrid coating showed a beneficial effect by reducing the pathogenicity of the internalized bacteria. The formation of biofilm was reduced by at least 50% in comparison to internalized bacteria by stromal cells on uncoated glass. This work opens the route for the development of innovative antibacterial coatings by taking into account the internalization of bacteria by stromal cells.

Mechanobiologically induced bone-like nodules: Matrix characterization from micro to nanoscale

In bone tissue engineering, stem cells are known to form inhomogeneous bone-like nodules on a micrometric scale. Herein, micro- and nano-infrared (IR) micro-spectroscopies were used to decipher the chemical composition of the bone-like nodule. Histological and immunohistochemical analyses revealed a cohesive tissue with bone-markers positive cells surrounded by dense mineralized type-I collagen. Micro-IR gathered complementary information indicating a non-mature collagen at the top and periphery and a mature collagen within the nodule. Atomic force microscopy combined to IR (AFM-IR) analyses showed distinct spectra of "cell" and "collagen" rich areas. In contrast to the "cell" area, spectra of "collagen" area revealed the presence of carbohydrate moieties of collagen and/or the presence of glycoproteins. However, it was not possible to determine the collagen maturity, due to strong bands overlapping and/or possible protein orientation effects. Such findings could help developing protocols to allow a reliable characterization of in vitro generated complex bone tissues.

Nanomaterials for Periodontal Tissue Engineering: Chitosan-Based Scaffolds. A Systematic Review

Introduction. Several biomaterials are used in periodontal tissue engineering in order to obtain a three-dimensional scaffold, which could enhance the oral bone regeneration. These novel biomaterials, when placed in the affected area, activate a cascade of events, inducing regenerative cellular responses, and replacing the missing tissue. Natural and synthetic polymers can be used alone or in combination with other biomaterials, growth factors, and stem cells. Natural-based polymer chitosan is widely used in periodontal tissue engineering. It presents biodegradability, biocompatibility, and biological renewability properties. It is bacteriostatic and nontoxic and has hemostatic and mucoadhesive capacity. The aim of this systematic review is to obtain an updated overview of the utilization and effectiveness of chitosan-based scaffold (CS-bs) in the alveolar bone regeneration process. Materials and Methods. During database searching (using PubMed, Cochrane Library, and CINAHL), 72 items were found. The title, abstract, and full text of each study were carefully analyzed and only 22 articles were selected. Thirteen articles were excluded based on their title, five after reading the abstract, twenty-six after reading the full text, and six were not considered because of their publication date (prior to 2010). Quality assessment and data extraction were performed in the twelve included randomized controlled trials. Data concerning cell proliferation and viability (CPV), mineralization level (M), and alkaline phosphatase activity (ALPA) were recorded from each article Results. All the included trials tested CS-bs that were combined with other biomaterials (such as hydroxyapatite, alginate, polylactic-co-glycolic acid, polycaprolactone), growth factors (basic fibroblast growth factor, bone morphogenetic protein) and/or stem cells (periodontal ligament stem cells, human jaw bone marrow-derived mesenchymal stem cells). Values about the proliferation of cementoblasts (CB) and periodontal ligament cells (PDLCs), the activity of alkaline phosphatase, and the mineralization level determined by pure chitosan scaffolds resulted in lower than those caused by chitosan-based scaffolds combined with other molecules and biomaterials. Conclusions. A higher periodontal regenerative potential was recorded in the case of CS-based scaffolds combined with other polymeric biomaterials and bioceramics (bio compared to those provided by CS alone. Furthermore, literature demonstrated that the addition of growth factors and stem cells to CS-based scaffolds might improve the biological properties of chitosan.