A novel gelatin/chitooligosaccharide/demineralized bone matrix composite scaffold and periosteum-derived mesenchymal stem cells for bone tissue engineering

Integrating Physical and Biochemical Cues for Muscle Engineering: Scaffolds and Graft Durability

Muscle stem cells (MuSCs) are essential for skeletal muscle regeneration, influenced by a complex interplay of mechanical, biochemical, and molecular cues. Properties of the extracellular matrix (ECM) such as stiffness and alignment guide stem cell fate through mechanosensitive pathways, where forces like shear stress translate into biochemical signals, affecting cell behavior. Aging introduces senescence which disrupts the MuSC niche, leading to reduced regenerative capacity via epigenetic alterations and metabolic shifts. Transplantation further challenges MuSC viability, often resulting in fibrosis driven by dysregulated fibro-adipogenic progenitors (FAPs). Addressing these issues, scaffold designs integrated with pharmacotherapy emulate ECM environments, providing cues that enhance graft functionality and endurance. These scaffolds facilitate the synergy between mechanotransduction and intracellular signaling, optimizing MuSC proliferation and differentiation. Innovations utilizing human pluripotent stem cell-derived myogenic progenitors and exosome-mediated delivery exploit bioactive properties for targeted repair. Additionally, 3D-printed and electrospun scaffolds with adjustable biomechanical traits tackle scalability in treating volumetric muscle loss. Advanced techniques like single-cell RNA sequencing and high-resolution imaging unravel muscle repair mechanisms, offering precise mapping of cellular interactions. Collectively, this interdisciplinary approach fortifies tissue graft durability and MuSC maintenance, propelling therapeutic strategies for muscle injuries and degenerative diseases.

Chondrogenic potential of PMSCs cultured on chondroitin sulfate/gelatin-modified DBM scaffold

Introduction

Osteoarthritis is one of the most common orthopedic diseases that gradually causes wear and damage to the articular Subchondral bone due to the destruction of articular cartilage. One of the basic challenges in cartilage tissue engineering is the choice of scaffold. In the design of the cartilage scaffold, it is useful to consider parameters such as porosity, water absorption, high mechanical resistance, biocompatibility, and biodegradability. Therefore, in this study, demineralized bone matrix (DBM), which inherently has these characteristics to some extent, was chosen as the basic scaffold.

Methods

The gelatin/DBM (G/DBM) and the chondroitin sulfate-gelatin/DBM (GCS/DBM) scaffolds were prepared, respectively, by incorporating gelatin or chondroitin sulfate/gelatin solution inside DBM pores, freeze-drying and crosslinking with EDC/NHS. The physicochemical, biological characteristics and chondrogenic potential of scaffolds were studied.

Results

According to the SEM results, the size of the DBM pores in the G/DBM and GCS/DBM scaffolds decreased (from almost 100-1500 µm to less than 200 µm), which reduced cell escape compared to the DBM scaffold. Also, crosslinking the scaffolds has greatly increased their compressive E-modulus (more than 8 times). The cytocompatibility and non- toxicity of all scaffolds were confirmed by acridine orange/ethidium bromide (AO/EB) staining. The evaluation results of chondrogenic differentiation of placenta-derived mesenchymal stem cells (PMSCs) on modified scaffolds, using the real-time PCR method, showed that the presence of CS in the GCS/DBM scaffold improved the expression of chondrogenesis markers such as Aggrecan (AGC) (~4 times) and collagen 2 (COL-2) (~2.2 times) compared to the DBM scaffold. Also, Alcian blue staining and immunohistochemical analyses of the scaffolds showed denser and more coherent GAGs and COL-2 protein synthesis on the GCS/DBM than the G/DBM and DBM scaffolds.

Conclusion

According to the results, the GCS/DBM scaffold can be a suitable scaffold for cartilage tissue engineering.

Current Perspectives of Protein in Bone Tissue Engineering: Bone Structure, Ideal Scaffolds, Fabrication Techniques, Applications, Scopes, and Future Advances

In view of their exceptional approach, excellent inherent biocompatibility and biodegradability properties, and interaction with the local extracellular matrix, protein-based polymers have received attention in bone tissue engineering, which is a multidisciplinary field that repairs and regenerates fractured bones. Bone is a multihierarchical complex structure, and it performs several essential biofunctions, including maintaining mineral balance and structural support and protecting soft organs. Protein-based polymers have gained interest in developing ideal scaffolds as emerging biomaterials for bone fractured healing and regeneration, and it is challenging to design ideal bone substitutes as perfect biomaterials. Several protein-based polymers, including collagen, keratin, gelatin, serum albumin, etc., are potential materials due to their inherent cytocompatibility, controlled biodegradability, high biofunctionalization, and tunable mechanical characteristics. While numerous studies have indicated the encouraging possibilities of proteins in BTE, there are still major challenges concerning their biodegradability, stability in physiological conditions, and continuous release of growth factors and bioactive molecules. Robust scaffolds derived from proteins can be used to replace broken or diseased bone with a biocompatible substitute; proteins, being biopolymers, provide excellent scaffolds for bone tissue engineering. Herein, recent developments in protein polymers for cutting-edge bone tissue engineering are addressed in this review within 3-5 years, with a focus on the significant challenges and future perspectives. The first section discusses the structural fundamentals of bone anatomy and ideal scaffolds, and the second section describes the fabrication techniques of scaffolds. The third section highlights the importance of proteins and their applications in BTE. Hence, the recent development of protein polymers for state-of-the-art bone tissue engineering has been discussed, highlighting the significant challenges and future perspectives.

Cell-Cultured Fish Meat via Scale-Up Expansion of Carassius auratus Skeletal Muscle Cells Using Edible Porous Microcarriers and Quality Evaluation

Emerging technologies for cell-cultured fish meat as an environmentally friendly protein source for humans still have many obstacles, including large-scale production of high-quality cells, differentiation and bioassembly of cellular material, and improvement of the quality of meat products. Here, we used edible porous microcarriers as scaffolds to support scalable skeletal muscle cell expansion to prepare centimeter-scale cell-cultured fish (CCM) of Carassius auratus for the first time. The quality of CCM was assessed by analyzing the texture, nutrition, flavor, and safety. The results indicated that CCM demonstrated a softer texture than natural fish due to a high moisture content. CCM contained higher protein and lower fat contents, with no significant difference in energy from natural golden crucian carp meat (NGM). CCM had better digestible properties, and 17 volatile components were identified in CCM, ten cocontained compared to NGM. ELISA quantified penicillin, streptomycin, vitamin D, and insulin residues as risk factors in CCM. In conclusion, we utilized edible porous microcarriers to scale-up the expansion of Carassius auratus skeletal muscle cells and bioassembled high-quality CCM of Carassius auratus for the first time, which represents a state-of-the-art protocol applicable to different fish species and even to other economic animals and provides a theoretical basis for scaling up cell-cultured meat production.

De novo design of a nanoregulator for the dynamic restoration of ovarian tissue in cryopreservation and transplantation

The cryopreservation and transplantation of ovarian tissue underscore its paramount importance in safeguarding reproductive capacity and ameliorating reproductive disorders. However, challenges persist in ovarian tissue cryopreservation and transplantation (OTC-T), including the risk of tissue damage and dysfunction. Consequently, there has been a compelling exploration into the realm of nanoregulators to refine and enhance these procedures. This review embarks on a meticulous examination of the intricate anatomical structure of the ovary and its microenvironment, thereby establishing a robust groundwork for the development of nanomodulators. It systematically categorizes nanoregulators and delves deeply into their functions and mechanisms, meticulously tailored for optimizing ovarian tissue cryopreservation and transplantation. Furthermore, the review imparts valuable insights into the practical applications and obstacles encountered in clinical settings associated with OTC-T. Moreover, the review advocates for the utilization of microbially derived nanomodulators as a potent therapeutic intervention in ovarian tissue cryopreservation. The progression of these approaches holds the promise of seamlessly integrating nanoregulators into OTC-T practices, thereby heralding a new era of expansive applications and auspicious prospects in this pivotal domain.

Micro/nanoengineered agricultural by-products for biomedical and environmental applications

Agriculturally derived by-products generated during the growth cycles of living organisms as secondary products have attracted increasing interest due to their wide range of biomedical and environmental applications. These by-products are considered promising candidates because of their unique characteristics including chemical stability, profound biocompatibility and offering a green approach by producing the least impact on the environment. Recently, micro/nanoengineering based techniques play a significant role in upgrading their utility, by controlling their structural integrity and promoting their functions at a micro and nano scale. Specifically, they can be used for biomedical applications such as tissue regeneration, drug delivery, disease diagnosis, as well as environmental applications such as filtration, bioenergy production, and the detection of environmental pollutants. This review highlights the diverse role of micro/nano-engineering techniques when applied on agricultural by-products with intriguing properties and upscaling their wide range of applications across the biomedical and environmental fields. Finally, we outline the future prospects and remarkable potential that these agricultural by-products hold in establishing a new era in the realms of biomedical science and environmental research.

Black Phosphorus-Based Dynamic Self-Healing Hydrogel to Integrate Demineralized Bone Matrix and Noggin-Targeting siRNA for Synergistic Osteogenesis

Although a demineralized bone matrix (DBM) is often used as an alternative to an autologous bone graft, its clinical application is still hampered by easy dispersion of DBM particles and insufficient osteoinductivity in the defect site. Herein, we designed a self-healing hydrogel for DBM that can rapidly restore its structural integrity after damage based on amino-rich black phosphorus (BP) nanosheets and aldehyde-functionalized hyaluronic acid (AHA). Given the increased expression of bone morphogenetic protein (BMP) antagonists by DBM stimulation, the osteogenic potency of DBM in the hydrogel carrier was further enhanced by abrogating the BMP antagonism. The BP/AHA hydrogel provided dynamic polymer-nanosheet networks that combine injectability, modability, and physical stability with high DBM loading, where the BP nanosheets served as osteogenic cross-linkers to promote biomineralization and deliver siRNA to suppress undesirable expression of BMP antagonist noggin by DBM. As a result, the BP/AHA hydrogel integrated with DBM and noggin-targeting siRNA synergistically promoted osteogenic differentiation of mesenchymal stem cells by enhancing BMP/Smad signaling. This work demonstrates a promising strategy to improve the efficacy of bone regeneration using bone graft.

Equine Musculoskeletal Pathologies: Clinical Approaches and Therapeutical Perspectives-A Review

Musculoskeletal injuries such as equine osteoarthritis, osteoarticular defects, tendonitis/desmitis, and muscular disorders are prevalent among sport horses, with a fair prognosis for returning to exercise or previous performance levels. The field of equine medicine has witnessed rapid and fruitful development, resulting in a diverse range of therapeutic options for musculoskeletal problems. Staying abreast of these advancements can be challenging, prompting the need for a comprehensive review of commonly used and recent treatments. The aim is to compile current therapeutic options for managing these injuries, spanning from simple to complex physiotherapy techniques, conservative treatments including steroidal and non-steroidal anti-inflammatory drugs, hyaluronic acid, polysulfated glycosaminoglycans, pentosan polysulfate, and polyacrylamides, to promising regenerative therapies such as hemoderivatives and stem cell-based therapies. Each therapeutic modality is scrutinized for its benefits, limitations, and potential synergistic actions to facilitate their most effective application for the intended healing/regeneration of the injured tissue/organ and subsequent patient recovery. While stem cell-based therapies have emerged as particularly promising for equine musculoskeletal injuries, a multidisciplinary approach is underscored throughout the discussion, emphasizing the importance of considering various therapeutic modalities in tandem.

Pioneering a paradigm shift in tissue engineering and regeneration with polysaccharides and proteins-based scaffolds: A comprehensive review

In the realm of modern medicine, tissue engineering and regeneration stands as a beacon of hope, offering the promise of restoring form and function to damaged or diseased organs and tissues. Central to this revolutionary field are biological macromolecules-nature's own blueprints for regeneration. The growing interest in bio-derived macromolecules and their composites is driven by their environmentally friendly qualities, renewable nature, minimal carbon footprint, and widespread availability in our ecosystem. Capitalizing on these unique attributes, specific composites can be tailored and enhanced for potential utilization in the realm of tissue engineering (TE). This review predominantly concentrates on the present research trends involving TE scaffolds constructed from polysaccharides, proteins and glycosaminoglycans. It provides an overview of the prerequisites, production methods, and TE applications associated with a range of biological macromolecules. Furthermore, it tackles the challenges and opportunities arising from the adoption of these biomaterials in the field of TE. This review also presents a novel perspective on the development of functional biomaterials with broad applicability across various biomedical applications.

Chitosan derived chito-oligosaccharides promote osteoblast differentiation and offer anti-osteoporotic potential: Molecular and morphological evidence from a zebrafish model

This study delves into the potential of chito-oligosaccharides (COS) to promote osteoblast differentiation and prevent osteoporosis, utilizing experiments with mouse MSCs and the zebrafish model. The preliminary biocompatibility study affirms the non-toxic nature of COS across various concentrations. In the osteoblast differentiation study, COS enhances ALP activity and calcium deposition at the cellular level. Moreover, COS induces the upregulation of molecular markers, including Runx2, Type I collagen, ALP, osteocalcin, and osteonectin in mouse MSCs. Zebrafish studies further demonstrate COS's anti-osteoporotic effects, showcasing its ability to expedite fin fracture repair, vertebral mineralization, and bone mineralization in dexamethasone-induced osteoporosis models. The scale regenerative study reveals that COS mitigates the detrimental effects of dexamethasone induced osteoclastic activity, reducing TRAP and hydroxyproline levels while elevating the expression of Runx2a MASNA isoform, collagen2α, OC, and ON mRNAs. Additionally, COS enhances calcium and phosphorus levels in regenerated scales, impacting the bone-healthy calcium-to‑phosphorus ratio. The study also suggests that COS modulates the MMP3-Osteopontin-MAPK signaling pathway. Overall, this comprehensive investigation underscores the potential of COS to prevent and treat osteoporosis. Its multifaceted cellular and molecular effects, combined with in vivo bone regeneration and repair, propose that COS may be effective in addressing osteoporosis and related bone disorders. Nonetheless, further research is imperative to unravel underlying mechanisms and optimize clinical applications.

Advancements in gelatin-based hydrogel systems for biomedical applications: A state-of-the-art review

A gelatin-based hydrogel system is a stimulus-responsive, biocompatible, and biodegradable polymeric system with solid-like rheology that entangles moisture in its porous network that gradually protrudes to assemble a hierarchical crosslinked arrangement. The hydrolysis of collagen directs gelatin construction, which retains arginyl glycyl aspartic acid and matrix metalloproteinase-sensitive degeneration sites, further confining access to chemicals entangled within the gel (e.g., cell encapsulation), modulating the release of encapsulated payloads and providing mechanical signals to the adjoining cells. The utilization of various types of functional tunable biopolymers as scaffold materials in hydrogels has become highly attractive due to their higher porosity and mechanical ability; thus, higher loading of proteins, peptides, therapeutic molecules, etc., can be further modulated. Furthermore, a stimulus-mediated gelatin-based hydrogel with an impaired concentration of gellan demonstrated great shear thinning and self-recovering characteristics in biomedical and tissue engineering applications. Therefore, this contemporary review presents a concise version of the gelatin-based hydrogel as a conceivable biomaterial for various biomedical applications. In addition, the article has recapped the multiple sources of gelatin and their structural characteristics concerning stimulating hydrogel development and delivery approaches of therapeutic molecules (e.g., proteins, peptides, genes, drugs, etc.), existing challenges, and overcoming designs, particularly from drug delivery perspectives.

Site-specific periosteal cells with distinct osteogenic and angiogenic characteristics

OBJECTIVES

This study aimed to investigate the site-specific characteristics of rat mandible periosteal cells (MPCs) and tibia periosteal cells (TPCs) to assess the potential application of periosteal cells (PCs) in bone tissue engineering (BTE).

MATERIALS AND METHODS

MPCs and TPCs were isolated and characterized. The potential of proliferation, migration, osteogenesis and adipogenesis of MPCs and TPCs were evaluated by CCK-8, scratch assay, Transwell assay, alkaline phosphatase staining and activity, Alizarin Red S staining, RT‒qPCR, and Western blot (WB) assays, respectively. Then, these cells were cocultured with human umbilical vein endothelial cells (HUVECs) to investigate their angiogenic capacity, which was assessed by scratch assay, Transwell assay, Matrigel tube formation assay, RT‒qPCR, and WB assays.

RESULTS

MPCs exhibited higher osteogenic potential, higher alkaline phosphatase activity, and more mineralized nodule formation, while TPCs showed a greater capability for proliferation, migration, and adipogenesis. MPCs showed higher expression of angiogenic factors, and the conditioned medium of MPCs accelerated the migration of HUVECs, while MPC- conditioned medium induced the formation of more tubular structure in HUVECs in vitro. These data suggest that compared to TPCs, MPCs exert more consequential proangiogenic effects on HUVECs.

CONCLUSIONS

PCs possess skeletal site-specific differences in biological characteristics. MPCs exhibit more eminent osteogenic and angiogenic potentials, which highlights the potential application of MPCs for BTE.

CLINICAL RELEVANCE

Autologous bone grafting as the main modality for maxillofacial bone defect repair has many limitations. Constituting an important cell type in bone repair and regeneration, MPCs show greater potential for application in BTE, which provides a promising treatment option for maxillofacial bone defect repair.

Baicalin Antagonizes Prostate Cancer Stemness via Inhibiting Notch1/NF-κB Signaling Pathway

OBJECTIVE

To investigate the molecular mechanisms underlying the effect of baicalin on prostate cancer (PCa) progression both in vivo and in vitro.

METHODS

The in situ PCa stem cells (PCSCs)-injected xenograft tumor models were established in BALB/c nude mice. Tumor volume and weight were respectively checked after baicalin (100 mg/kg) treatment. Hematoxylin-eosin (HE) staining was used to observe the growth arrest and cell necrosis. mRNA expression levels of acetaldehyde dehydrogenase 1 (ALDH1), CD44, CD133 and Notch1 were determined by reverse transcription-polymerase chain reaction. Protein expression levels of ALDH1, CD44, CD133, Notch1, nuclear factor κB (NF-κB) P65 and NF-κB p-P65 were detected by Western blot. Expression and subcellular location of ALDH1, CD44, CD133, Notch1 and NF-κB p65 were detected by immunofluorescence analysis. In vitro, cell cycle distribution and cell apoptosis of PC3 PCSCs was assessed by flow cytometry after baicalin (125 µmol/L) treatment. The migration and invasion abilities of PCSCs were assessed using Transwell assays. Transmission electron microscopy scanning was utilized to observe the structure and autophagosome formation of baicalin-treated PCSCs. In addition, PCSCs were infected with lentiviruses expressing human Notch1.

RESULTS

Compared with the control group, the tumor volume and weight were notably reduced in mice treated with 100 mg/kg baicalin (P<0.05 or P<0.01). Histopathological analysis showed that baicalin treatment significantly inhibited cell proliferation and promoted cell apoptosis. Furthermore, baicalin treatment reduced mRNA and protein expression levels of CD44, CD133, ALDH1, and Notch1 as well as the protein expression of NF-κB p-P65 in the xenograft tumor (P<0.01). In vitro, the cell proliferation of PCSCs was significantly attenuated after treatment with 125 µmol/L baicalin for 72 h (P<0.01). The cell migration and invasion rates were decreased following treatment with baicalin for 48 and 72 h (P<0.01). Baicalin notably induced cell apoptosis and seriously damaged the structure of PCSCs. The mRNA and protein expressions of CD133, CD44, ALDH1 and Notch1 in PCSCs were significantly downregulated following baicalin treatment (P<0.01). Importantly, the inhibitory effects of baicalin on PCa progression and stemness were reversed by Notch1 overexpression (P<0.05 or P<0.01).

CONCLUSION

Mechanistically, baicalin exhibited a potential therapeutic effect on PCa via inhibiting the Notch1/NF-κB signaling pathway and its mediated cancer stemness.

Functionalized acellular periosteum guides stem cell homing to promote bone defect repair

The periosteum plays a key role in bone tissue regeneration, especially in the promotion and protection of new bones. However, among the bone repair materials, many biomimetic artificial periosteum lack the natural periosteal structure, stem cells, and immunoregulation required for bone regeneration. In this study, we used natural periosteum to produce acellular periosteum. To retain the appropriate cell survival structure and immunomodulatory proteins, we grafted the functional polypeptide SKP on the surface collagen of the periosteum via an amide bond, providing the acellular periosteum with the ability to recruit mesenchymal stem cells. Thus, we developed a biomimetic periosteum (DP-SKP) with the ability to promote stem cell homing and immunoregulation in vivo. Compared to the blank and simple decellularized periosteum groups, DP-SKP was more conducive to stem cell adhesion, growth, and osteogenic differentiation in vitro. Additionally, compared with the other two groups, DP-SKP significantly promoted mesenchymal stem cell homing to the periosteal transplantation site, improved the bone immune microenvironment, and accelerated new lamellar bone formation in the critical size defect of rabbit skulls in vivo. Therefore, this acellular periosteum with a mesenchymal stem cell homing effect is expected to be used as an extracellular artificial periosteum in clinical practice.

3D printing of chitooligosaccharide-polyethylene glycol diacrylate hydrogel inks for bone tissue regeneration

To date, lack of functional hydrogel inks has limited 3D printing applications in tissue engineering. This study developed a series of photocurable hydrogel inks based on chitooligosaccharide (COS)-polyethylene glycol diacrylate (PEGDA) for extrusion-based 3D printing of bone tissue scaffolds. The scaffolds were prepared by aza-Michael addition of COS and PEGDA followed by photopolymerisation of unreacted PEGDA. The hydrogel inks showed sufficient shear thinning properties required for extrusion 3D printing. The printed scaffolds exhibited excellent shape fidelity and fine microstructure with a resolution of 250 μm. By increasing the COS content, the swelling ratio of the scaffolds decreased, while the compressive strength increased. 3D printed COS-PEGDA scaffolds showed high viability of human bone mesenchymal stem cells in vitro. In addition, scaffolds containing 2 wt% COS showed significantly higher alkaline phosphatase activity, calcium deposition, and bioactivity in simulated body fluid compared to the control (PEGDA). Altogether, 3D printed COS-PEGDA scaffolds represent promising candidates for bone tissue regeneration.

A Comparative Study of HA/DBM Compounds Derived from Bovine and Porcine for Bone Regeneration

This comparative study investigated the tissue regeneration and inflammatory response induced by xenografts comprised of hydroxyapatite (HA) and demineralized bone matrix (DBM) extracted from porcine (P) and bovine (B) sources. First, extraction of HA and DBM was independently conducted, followed by chemical and morphological characterization. Second, mixtures of HA/DBM were prepared in 50/50 and 60/40 concentrations, and the chemical, morphological, and mechanical properties were evaluated. A rat calvarial defect model was used to evaluate the tissue regeneration and inflammatory responses at 3 and 6 months. The commercial allograft DBM Puros® was used as a clinical reference. Different variables related to tissue regeneration were evaluated, including tissue thickness regeneration (%), amount of regenerated bone area (%), and amount of regenerated collagen area (%). The inflammatory response was evaluated by quantifying the blood vessel area. Overall, tissue regeneration from porcine grafts was superior to bovine. After 3 months of implantation, the tissue thickness regeneration in the 50/50P compound and the commercial DBM was significantly higher (~99%) than in the bovine materials (~23%). The 50/50P and DBM produced higher tissue regeneration than the naturally healed controls. Similar trends were observed for the regenerated bone and collagen areas. The blood vessel area was correlated with tissue regeneration in the first 3 months of evaluation. After 6 months of implantation, HA/DBM compounds showed less regenerated collagen than the DBM-only xenografts. In addition, all animal-derived xenografts improved tissue regeneration compared with the naturally healed defects. No clinical complications associated with any implanted compound were noted.

A review on background, process and application of electrospun nanofibers for tissue regeneration

Electrospinning is a versatile method which is used to synthesize nano/micro sized fibers under the influence of electric field. Electrospun nanoscaffolds are one of the widely accepted platforms for cultivating soft and hard tissues as they create a prefect micro-environment for cell adhesion, proliferation and differentiation. Nanoscaffolds are widely used in the field of tissue engineering due to their versatility in aiding the growth of different types of cells and tissues for varied applications. The composition, molecular weight and structure of polymer used to fabricate nanoscaffold plays an important role in determining the size and strength of the nanofibers prepared. This review gives information about the background, process and different types of polymers used in electrospinning. Recent advances in culturing liver cells, osteoblasts, skin cells, neural cells and coronary artery smooth muscle cells on nanoscaffolds are also elucidated.

[Preparation and bone repair capability of a new plastic bone filler material]

Objective

To prepare a new plastic bone filler material with adhesive carrier and matrix particles derived from human bone, and evaluate its safety and osteoinductive ability through animal tests.

Methods

The human long bones donated voluntarily were prepared into decalcified bone matrix (DBM) by crushing, cleaning, and demineralization, and then the DBM was prepared into bone matrix gelatin (BMG) by warm bath method, and the BMG and DBM were mixed to prepare the experimental group's plastic bone filler material; DBM was used as control group. Fifteen healthy male thymus-free nude mice aged 6-9 weeks were used to prepare intermuscular space between gluteus medius and gluteus maximus muscles, and all of them were implanted with experimental group materials. The animals were sacrificed at 1, 4, and 6 weeks after operation, and the ectopic osteogenic effect was evaluated by HE staining. Eight 9-month-old Japanese large-ear rabbits were selected to prepare 6-mm-diameter defects at the condyles of both hind legs, and the left and right sides were filled with the materials of the experimental group and the control group respectively. The animals were sacrificed at 12 and 26 weeks after operation, and the effect of bone defect repair were evaluated by Micro-CT and HE staining.

Results

In ectopic osteogenesis experiment, HE staining showed that a large number of chondrocytes could be observed at 1 week after operation, and obvious newly formed cartilage tissue could be observed at 4 and 6 weeks after operation. For the rabbit condyle bone filling experiment, HE staining showed that at 12 weeks after operation, part of the materials were absorbed, and new cartilage could be observed in both experimental and control groups; at 26 weeks after operation, the most of the materials were absorbed, and large amount of new bone could be observed in the 2 groups, while new bone unit structure could be observed in the experimental group. Micro-CT observation showed that the bone formation rate and area of the experimental group were better than those of the control group. The measurement of bone morphometric parameters showed that the parameters at 26 weeks after operation in both groups were significantly higher than those at 12 weeks after operation ( P<0.05). At 12 weeks after operation, the bone mineral density and bone volume fraction in the experimental group were significantly higher than those in the control group ( P<0.05), and there was no significant difference between the two groups in trabecular thickness ( P>0.05). At 26 weeks after operation, the bone mineral density of the experimental group was significantly higher than that of the control group ( P<0.05). There was no significant difference in bone volume fraction and trabecular thickness between the two groups ( P>0.05).

Conclusion

The new plastic bone filler material is an excellent bone filler material with good biosafety and osteoinductive activity.

The differentiation of human induced pluripotent stem cells into hematopoietic stem cells on 3D bone scaffold in a dynamic culture system

Hematopoietic stem cell transplantation is used for cell-based therapy for many hematological disorders. However, difficulty in finding proper donors has limited this source of stem cells. For clinical application, the generation of these cells from induced pluripotent stem cells (iPSs) is a fascinating and endless source. One of the experimental methods to generate HSCs from iPSs is the mimicking of the hematopoietic niche. In the current study, as the first phase of differentiation, embryoid bodies were formed from iPSs. They were then cultured in different dynamic conditions in order to determine the appropriate settings for their differentiation into HSCs. The dynamic culture was composed of DBM Scaffold with or without growth factor. After ten days, the specific HSC markers (CD34, CD133, CD31 and CD45) were assessed using flow-cytometry. Our findings demonstrated that the dynamic conditions were significantly suitable than static ones. In addition, in 3D scaffold and dynamic system the expression of CXCR4, as a homing marker, was increased. These results suggest that the 3D culture bioreactor with DBM scaffold could provide a new approach for differentiation of iPSs into HSCs. Moreover, this system could provide maximum mimicry of bone marrow niche.

Standard in vitro evaluations of engineered bone substitutes are not sufficient to predict in vivo preclinical model outcomes

Understanding the optimal conditions required for bone healing can have a substantial impact to target the problem of non-unions and large bone defects. The combination of bioactive factors, regenerative progenitor cells and biomaterials to form a tissue engineered (TE) complex is a promising solution but translation to the clinic has been slow. We hypothesized the typical material testing algorithm used is insufficient and leads to materials being mischaracterized as promising. In the first part of this study, human bone marrow - derived mesenchymal stromal cells (hBM-MSCs) were embedded in three commonly used biomaterials (hyaluronic acid methacrylate, gelatin methacrylate and fibrin) and combined with relevant bioactive osteogenesis factors (dexamethasone microparticles and polyphosphate nanoparticles) to form a TE construct that underwent in vitro osteogenic differentiation for 28 days. Gene expression of relevant transcription factors and osteogenic markers, and von Kossa staining were performed. In the second and third part of this study, the same combination of TE constructs were implanted subcutaneously (cell containing) in T cell-deficient athymic Crl:NIH-Foxn1^rnu rats for 8 weeks or cell free in an immunocompetent New Zealand white rabbit calvarial model for 6 weeks, respectively. Osteogenic performance was investigated via MicroCT imaging and histology staining. The in vitro study showed enhanced upregulation of relevant genes and significant mineral deposition within the three biomaterials, generally considered as a positive result. Subcutaneous implantation indicates none to minor ectopic bone formation. No enhanced calvarial bone healing was detected in implanted biomaterials compared to the empty defect. The reasons for the poor correlation of in vitro and in vivo outcomes are unclear and needs further investigation. This study highlights the discrepancy between in vitro and in vivo outcomes, demonstrating that in vitro data should be interpreted with extreme caution. In vitro models with higher complexity are necessary to increase value for translational studies. STATEMENT OF SIGNIFICANCE: Preclinical testing of newly developed biomaterials is a crucial element of the development cycle. Despite this, there is still significant discrepancy between in vitro and in vivo test results. Within this study we investigate multiple combinations of materials and osteogenic stimulants and demonstrate a poor correlation between the in vitro and in vivo data. We propose rationale for why this may be the case and suggest a modified testing algorithm.

High yield engineered nanovesicles from ADSC with enriched miR-21-5p promote angiogenesis in adipose tissue regeneration

BACKGROUND

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been found to have a great potential for soft tissue repair due to various biological functions, including pro-angiogenesis and low immunogenicity. However, the low yield and heterogeneity of MSC-EVs limited their clinical transformation. This study was designed to develop a novel adipose-derived stem cell engineered nanovesicles (ADSC-NVs) with high production and explore its pro-angiogenetic effect and application in adipose tissue regeneration.

METHODS

Adipose-derived stem cell-derived extracellular vesicles (ADSC-EVs) were isolated from an EVs-free culture medium for human ADSCs (hADSCs). ADSC-NVs were prepared by sequentially extruding ADSCs followed by iodixanol density gradient ultracentrifugation and were compared with ADSC-EVs in morphology, size distribution, protein contents and yield. The pro-angiogenetic effect of ADSC-NVs in different doses (0, 5, 20 and 80 μg/mL) in vitro was determined using transwell assay, tube formation assay, western blot and qRT-PCR. In vivo, BALB/c nude mice were administered injection of a mixture of fat granules and different dose of ADSC-NVs and grafts were harvested at 12 weeks post-transplantation for further analysis. By analyzing the weight and volume of grafts and histological evaluation, we investigated the effect of ADSC-NVs in vessel formation and adipose tissue regeneration.

RESULTS

Our results showed yield of purified ADSC-NVs was approximately 20 times more than that of ADSC-EVs secreted by the same number of ADSCs. In vitro, both ADSC-NVs and ADSC-EVs exhibited a dose-dependent pro-angiogenetic effect, despite their distinct miRNA profiles. These effects of ADSC-NVs may be mediated by enriched miR-21-5p via PTEN inhibition and PI3K/p-Akt signaling activation. Furthermore, after a mixed injection of ADSC-NVs, vessel formation and adipose regeneration were observed in vivo in fat implants.

CONCLUSIONS

Our study developed a potent alternative of ADSC-EVs. ADSC-NVs have a high pro-angiogenesis potential and can be used as cell-free therapeutic biomaterials in soft tissue regeneration.

Scaffold Fabrication Techniques of Biomaterials for Bone Tissue Engineering: A Critical Review

Bone tissue engineering (BTE) is a promising alternative to repair bone defects using biomaterial scaffolds, cells, and growth factors to attain satisfactory outcomes. This review targets the fabrication of bone scaffolds, such as the conventional and electrohydrodynamic techniques, for the treatment of bone defects as an alternative to autograft, allograft, and xenograft sources. Additionally, the modern approaches to fabricating bone constructs by additive manufacturing, injection molding, microsphere-based sintering, and 4D printing techniques, providing a favorable environment for bone regeneration, function, and viability, are thoroughly discussed. The polymers used, fabrication methods, advantages, and limitations in bone tissue engineering application are also emphasized. This review also provides a future outlook regarding the potential of BTE as well as its possibilities in clinical trials.

Comparative evaluation of mesenchymal stromal cell growth and osteogenic differentiation on a shape memory polymer scaffold

Trauma-induced, critical-size bone defects pose a clinical challenge to heal. Albeit autografts are the standard-of-care, they are limited by their inability to be shaped to various defect geometries and often incur donor site complications. Herein, the combination of a "self-fitting" shape memory polymer (SMP) scaffold and seeded mesenchymal stromal cells (MSCs) was investigated as an alternative. The porous SMP scaffold, prepared from poly(ε-caprolactone) diacrylate (PCL-DA) and coated with polydopamine, provided conformal shaping and cell adhesion. MSCs from five tissues, amniotic (AMSCs), chorionic tissue (CHSCs), umbilical cord (UCSCs), adipose (ADSCs), and bone marrow (BMSCs) were evaluated for viability, density, and osteogenic differentiation on the SMP scaffold. BMSCs exhibited the fastest increase in cell density by day 3, but after day 10, CHSCs, UCSCs, and ADSCs approached similar cell density. BMSCs also showed the greatest calcification among the cell types, followed closely by ADSCs, CHSCs and AMSCs. Alkaline phosphatase (ALP) activity peaked at day 7 for AMSCs, UCSCs, ADSCs and BMSCs, and at day 14 for CHSCs, which had the greatest overall ALP activity. Of all the cell types, only scaffolds cultured with ADSCs in osteogenic media had increased hardness and local modulus as compared to blank scaffolds after 21 days of cell culture and osteogenic differentiation. Overall, ADSCs performed most favorably on the SMP scaffold. The SMP scaffold was able to support key cellular behaviors of MSCs and could potentially be a viable, regenerative alternative to autograft.

P, Arora V, Sachdeva K, Sharma H, Dinda AK, Agrawal AK, Jassal M, Mohanty S. Promoting in-vivo bone regeneration using facile engineered load-bearing 3D bioactive scaffold

The worldwide incidence of bone disorders has trended steeply upward and is expected to get doubled by 2030. Biological mechanism of bone repair involves both osteo-conductivity and osteo-inductivity. In spite of the self-healing functionality after injury, bone tissue faces multitude of pathological challenges. Several innovative approaches have been developed to prepare biomaterial-based bone grafts. To design a suitable bone material, the freeze-drying technique has achieved significant importance among the other conventional methods. However, the functionality of the polymeric freeze-dried scaffold in in-vivo osteogenesis is in nascent stage. In this study facile, freeze dried, biomaterial-based load bearing 3D porous composite scaffolds have been prepared. The biocompatible scaffolds have been made by using chitosan (C), polycaprolactone (P), hydroxyapatite (H), glass ionomer (G), and graphene (gr). Scaffolds of eight different groups (C, P, CP, CPH, CPHG, CPHGgr1, CPHGgr2, CPHGgr3) have been designed and characterized to evaluate their applicability in orthopaedics. To evaluate the efficacy of the scaffolds a series of physio-chemical, morphological, and in-vitro & in-vivo biological experiments have been performed. From the obtained results it was observed that the CPHGgr1 is the ideal compatible material for Wharton’s Jelly derived mesenchymal stem cells and the blood cells. The in-vitro bone specific gene expression study revealed that, the scaffold assists MSCs osteogenic differentiation. Additionally, the in-vivo study on mice model was also performed for a period of 4 weeks and 8 weeks. The sub-cutaneous implantation of the designed scaffolds didn’t show any altered physiological condition in the animals, which indicated the in-vivo biocompatibility of the designed material. The histopathological study revealed that after 8 weeks of implantation, the CPHGgr1 scaffold supported significantly better collagen deposition and calcification. The facile designing of CPHGgr1 multicomponent nanocomposite provided an osteo-regenerative biomaterial with desired mechanical strength as an ideal regenerative material for cancellous bone tissue regeneration.

Mineralization in a Critical Size Bone-Gap in Sheep Tibia Improved by a Chitosan-Calcium Phosphate-Based Composite as Compared to Predicate Device

Deacetylated chitin derivatives have been widely studied for tissue engineering purposes. This study aimed to compare the efficacy of an injectable product containing a 50% deacetylated chitin derivative (BoneReg-Inject™) and an existing product (chronOS Inject^®) serving as a predicate device. A sheep model with a critical size drill hole in the tibial plateau was used. Holes of 8 mm diameter and 30 mm length were drilled bilaterally into the proximal area of the tibia and BoneReg-Inject™ or chronOS Inject^® were injected into the right leg holes. Comparison of resorption and bone formation in vivo was made by X-ray micro-CT and histological evaluation after a live phase of 12 weeks. Long-term effects of BoneReg-Inject™ were studied using a 13-month live period. Significant differences were observed in (1) amount of new bone within implant (p < 0.001), higher in BoneReg-Inject^TM, (2) signs of cartilage tissue (p = 0.003), more pronounced in BoneReg-Inject^TM, and (3) signs of fibrous tissue (p < 0.001), less pronounced in BoneReg-Inject^TM. Mineral content at 13 months postoperative was significantly higher than at 12 weeks (p < 0.001 and p < 0.05, for implant core and rim, respectively). The data demonstrate the potential of deacetylated chitin derivatives to stimulate bone formation.

Polyphenols-loaded electrospun nanofibers in bone tissue engineering and regeneration

Bone is a complex structure with unique cellular and molecular process in its formation. Bone tissue regeneration is a well-organized and routine process at the cellular and molecular level in humans through the activation of biochemical pathways and protein expression. Though many forms of biomaterials have been applied for bone tissue regeneration, electrospun nanofibrous scaffolds have attracted more attention among researchers with their physicochemical properties such as tensile strength, porosity, and biocompatibility. When drugs, antibiotics, or functional nanoparticles are taken as additives to the nanofiber, its efficacy towards the application gets increased. Polyphenol is a versatile green/phytochemical small molecule playing a vital role in several biomedical applications, including bone tissue regeneration. When polyphenols are incorporated as additives to the nanofibrous scaffold, their combined properties enhance cell attachment, proliferation, and differentiation in bone tissue defect. The present review describes bone biology encompassing the composition and function of bone tissue cells and exemplifies the series of biological processes associated with bone tissue regeneration. We have highlighted the molecular mechanism of bioactive polyphenols involved in bone tissue regeneration and specified the advantage of electrospun nanofiber as a wound healing scaffold. As the polyphenols contribute to wound healing with their antioxidant and antimicrobial properties, we have compiled a list of polyphenols studied, thus far, for bone tissue regeneration along with their in vitro and in vivo experimental biological results and salient observations. Finally, we have elaborated on the importance of polyphenol-loaded electrospun nanofiber in bone tissue regeneration and discussed the possible challenges and future directions in this field.