Nanocomposite scaffold seeded with mesenchymal stem cells for bone repair

Development and application of hydroxyapatite-based scaffolds for bone tissue regeneration: A systematic literature review

Hydroxyapatite [HA, Ca10(PO4)6(OH)2], with its robust biocompatibility and bioactivity, has found extensive utility in bone grafting, replacement therapies, and supplemental medical materials. HA is highly regarded for its osteoconductive properties because it boasts hydrophilicity, nontoxicity, non-allergenicity, and non-mutagenicity. Nevertheless, HA's intrinsic mechanical weakness has spurred efforts to enhance its properties. This enhancement is achieved through ion incorporation, with elements such as magnesium, zinc, lithium, strontium, boron, and others being integrated into the HA structure. In the domain of orthopedics, HA-based scaffolds have emerged as a solution for addressing prevalent issues like bone deformities and defects stemming from congenital anomalies, injuries, trauma, infections, or tumors. The fabrication of three-dimensional scaffolds (3D scaffolds) has enabled advancements in bone regeneration and replacement, with a focus on practical applications such as repairing calvarial, skull, and femoral defects. In vitro and in vivo assessments have substantiated the effectiveness of 3D scaffolds for bone defect repair, regeneration, and tissue engineering. Beyond bone-related applications, scaffolds demonstrate versatility in enhancing cartilage healing and serving as bioimplants. The wide array of scaffold applications underscores their ongoing potential for further development in the realm of medical science.

Drug Loaded 3D-Printed Poly(ε-Caprolactone) Scaffolds for Local Antibacterial or Anti-Inflammatory Treatment in Bone Regeneration

Annual bone grafting surgeries due to bone fractures, resections of affected bones, skeletal anomalies, osteoporosis, etc. exceed two million worldwide. In this regard, the creation of new materials for bone tissue repair is one of the urgent tasks of modern medicine. Additive manufacturing, or 3D printing, offers great opportunities for the development of materials with diverse properties and designs. In this study, the one-pot technique for the production of 3D scaffolds based on poly(ε-caprolactone) (PCL) loaded with an antibiotic or anti-inflammatory drug was proposed. In contrast to previously described methods to prepare drug-containing scaffolds, drug-loaded PCL scaffolds were prepared by direct 3D printing from a polymer/drug blend. An investigation of the mechanical properties of 3D-printed scaffolds containing 0.5-5 wt% ciprofloxacin (CIP) or dexamethasone (DEX) showed almost no effect of the drug (compression modulus ~70-90 MPa) compared to unfilled PCL (74 MPa). At the same time, introducing the drug and increasing its content in the PCL matrix contributed to a 1.8-6.8-fold decrease in the specific surface area of the scaffold, depending on composition. The release of CIP and DEX in phosphate buffer solution and in the same buffer containing lipase revealed a faster release in enzyme-containing medium within 45 days. Furthermore, drug release was more intensive from scaffolds with a low drug load. Analysis of the release profiles using a number of mathematical dissolution models led to the conclusion that diffusion dominates over other probable factors. In vitro biological evaluation of the scaffolds containing DEX showed moderate toxicity against osteoblast-like and leukemia monocytic cells. Being 3D-printed together with PCL both drugs retain their biological activity. PCL/CIP and PCL/DEX scaffolds demonstrated antibacterial properties against Pseudomonas aeruginosa (a total inhibition after 48 h) and anti-inflammatory activity in experiments on TNFα-activated monocyte cells (a 4-time reduction in CD-54 expression relative to control), respectively.

Biocompatibility and interaction of porous alumina-zirconia scaffolds with adipose-derived mesenchymal stem cells for bone tissue regeneration

Replacement of bone defects with bone graft or implant is an important therapeutic strategy that has been used in routine practice. However, the identification of biomaterials that can mimic natural bone properties and serve as bone substitutes remains a major challenge. In this context, alumina-zirconia (Al2O3/ZrO2) nanocomposites emerge as potential alternatives for biomedical applications, owing to their high mechanical strength, wear resistance, and biocompatibility. In this sense, in this study, we prepared porous Al2O3/ZrO2 nanocomposites (scaffolds) using the gelcasting method and biomimetically coated them with calcium phosphate (CaP). We evaluated the biocompatibility of the scaffolds using the quantitative MTT cytotoxicity test in L929 cells. Moreover, rabbit adipose-derived mesenchymal stem cells (rADMSCs) were seeded with CaP-containing and CaP-free porous samples to evaluate cell proliferation and cell-scaffold interaction in vitro. Our results showed that the Al2O3/ZrO2 scaffolds were non-cytotoxic, and there were no significant differences between CaP-containing and CaP-free scaffolds in terms of cell growth and adhesion. In contrast, when co-cultured with rADMSCs, the scaffolds enhanced cell proliferation and cell adhesion. The rADMSCs adhered and migrated through the pores of the scaffold and anchored to different poles with differentiated elongated structures. These results suggest osteogenic differentiation of rADMSCs in response to mechanical loading of Al2O3/ZrO2 scaffolds. Therefore, we conclude that Al2O3/ZrO2 scaffolds have demonstrated significant implications in bone tissue engineering and are valuable biomaterials for bone replacement.

Bone mesenchymal stem cells stimulation by magnetic nanoparticles and a static magnetic field: release of exosomal miR-1260a improves osteogenesis and angiogenesis

Background

The therapeutic potential of exosomes derived from stem cells has attracted increasing interest recently, because they can exert similar paracrine functions of stem cells and overcome the limitations of stem cells transplantation. Exosomes derived from bone mesenchymal stem cells (BMSC-Exos) have been confirmed to promote osteogenesis and angiogenesis. The magnetic nanoparticles (eg. Fe₃O₄, γ-Fe₂O₃) combined with a static magnetic field (SMF) has been commonly used to increase wound healing and bone regeneration. Hence, this study aims to evaluate whether exosomes derived from BMSCs preconditioned with a low dose of Fe₃O₄ nanoparticles with or without the SMF, exert superior pro-osteogenic and pro-angiogenic activities in bone regeneration and the underlying mechanisms involved.

Methods

Two novel types of exosomes derived from preconditioned BMSCs that fabricated by regulating the contents with the stimulation of magnetic nanoparticles and/or a SMF. Then, the new exosomes were isolated by ultracentrifugation and characterized. Afterwards, we conducted in vitro experiments in which we measured osteogenic differentiation, cell proliferation, cell migration, and tube formation, then established an in vivo critical-sized calvarial defect rat model. The miRNA expression profiles were compared among the exosomes to detect the potential mechanism of improving osteogenesis and angiogenesis. At last, the function of exosomal miRNA during bone regeneration was confirmed by utilizing a series of gain- and loss-of-function experiments in vitro.

Results

50 µg/mL Fe₃O₄ nanoparticles and a 100 mT SMF were chosen as the optimum magnetic conditions to fabricate two new exosomes, named BMSC-Fe₃O₄-Exos and BMSC-Fe₃O₄-SMF-Exos. They were both confirmed to enhance osteogenesis and angiogenesis in vitro and in vivo compared with BMSC-Exos, and BMSC-Fe₃O₄-SMF-Exos had the most marked effect. The promotion effect was found to be related to the highly riched miR-1260a in BMSC-Fe₃O₄-SMF-Exos. Furthermore, miR-1260a was verified to enhance osteogenesis and angiogenesis through inhibition of HDAC7 and COL4A2, respectively.

Conclusion

These results suggest that low doses of Fe₃O₄ nanoparticles combined with a SMF trigger exosomes to exert enhanced osteogenesis and angiogenesis and that targeting of HDAC7 and COL4A2 by exosomal miR-1260a plays a crucial role in this process. This work could provide a new protocol to promote bone regeneration for tissue engineering in the future.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00958-6.

Bone Growth Capacity of Human Umbilical Cord Mesenchymal Stem Cells and BMP-2 Seeded Into Hydroxyapatite/Chitosan/Gelatin Scaffold in Alveolar Cleft Defects: An Experimental Study in Goat

OBJECTIVE

To evaluate bone regeneration in alveolar defects treated with human umbilical cord-derived mesenchymal stem cells (hUCMSCs), hydroxyapatite/chitosan/gelatin (HA/CS/Gel) scaffold, and bone morphogenic protein-2 (BMP-2) in Capra hircus models.

DESIGN

Randomized posttest-only control group design.

SETTING

Animal Hospital at Bogor Agricultural Institute.

PARTICIPANTS

Healthy and equally treated 24 female Capra hircus/goats.

INTERVENTION

Animals were randomly assigned to 3 experimental group design (iliac crest alveolar bone graft/ICABG [control], HA/Cs/Gel+BMP-2 [Novosys], and HA/Cs/Gel+BMP-2+UCMSCs). Graft materials were implanted in surgically made alveolar defects.

MAIN OUTCOME MEASURES

Postoperative functional score and operating time were assessed. New bone growth, bone density, inflammatory cells recruitment, and neoangiogenesis were evaluated based on radiological and histological approach at 2 time points, week 4 and 12. Statistical analysis was done between treatment groups.

RESULTS

Operating time was 34% faster and functional score 94.5% more superior in HA/Cs/Gel+BMP-2+hUCMSC group. Bone growth capacity in HA/Cs/Gel+BMP-2+UCMSCs mimicked ICABG, but ICABG showed possibility of bone loss between week 4 and 12. The HA/Cs/Gel+BMP-2+UCMSCs showed early bone repopulation and unseen inflammatory cells and angiogenesis on week 12.

DISCUSSION AND CONCLUSION

The HA/Cs/Gel+BMP-2+hUCMSCs were superior in enhancing new bone growth without donor site morbidity compared to ICABG. The presence of hUCMSCs in tissue-engineered alveolar bone graft (ABG), supported with paracrine activity of the resident stem cells, initiated earlier new bone repopulation, and completed faster bone regeneration. The HA/Cs/Gel scaffold seeded with UCMSCs+BMP-2 is a safe substitute of ICABG to close alveolar bone defects suitable for patients with cleft lip, alveolus, and palate.