Rotary Jet-Spun Polycaprolactone/Hydroxyapatite and Carbon Nanotube Scaffolds Seeded with Bone Marrow Mesenchymal Stem Cells Increase Bone Neoformation

Spatially controlled multicellular differentiation of stem cells using triple factor-releasing metal-organic framework-coated nanoline arrays

Improved in vitro models are needed for regenerative therapy and drug screening. Here, we report on functionally aligned nanoparticle-trapped nanopattern arrays for spatially controlled, precise mesenchymal stem cell differentiation on a single substrate. The arrays comprise nanohole and nanoline arrays fabricated through interference lithography and selectively capture of UiO-67 metal-organic frameworks on nanoline arrays with a 99.8% efficiency using an optimised asymmetric spin-coating method. The UiO-67 metal-organic frameworks contain three osteogenic differentiation factors for sustained release over four weeks. The combination of differentiation factors and patterned array allows for generation of adipocytes, osteoblasts, and adipocyte-osteoblast mixtures on nanohole arrays, nanoline arrays, and at the nanohole-nanoline interface, respectively, with mature osteoblasts exhibiting higher marker expression and mineralisation. The sustained release patterned array holds potential for constructing advanced therapeutic and disease state in vitro cellular models.

New Generation of Osteoinductive and Antimicrobial Polycaprolactone-Based Scaffolds in Bone Tissue Engineering: A Review

With respect to other fields, bone tissue engineering has significantly expanded in recent years, leading not only to relevant advances in biomedical applications but also to innovative perspectives. Polycaprolactone (PCL), produced in the beginning of the 1930s, is a biocompatible and biodegradable polymer. Due to its mechanical and physicochemical features, as well as being easily shapeable, PCL-based constructs can be produced with different shapes and degradation kinetics. Moreover, due to various development processes, PCL can be made as 3D scaffolds or fibres for bone tissue regeneration applications. This outstanding biopolymer is versatile because it can be modified by adding agents with antimicrobial properties, not only antibiotics/antifungals, but also metal ions or natural compounds. In addition, to ameliorate its osteoproliferative features, it can be blended with calcium phosphates. This review is an overview of the current state of our recent investigation into PCL modifications designed to impair microbial adhesive capability and, in parallel, to allow eukaryotic cell viability and integration, in comparison with previous reviews and excellent research papers. Our recent results demonstrated that the developed 3D constructs had a high interconnected porosity, and the addition of biphasic calcium phosphate improved human cell attachment and proliferation. The incorporation of alternative antimicrobials-for instance, silver and essential oils-at tuneable concentrations counteracted microbial growth and biofilm formation, without affecting eukaryotic cells' viability. Notably, this challenging research area needs the multidisciplinary work of material scientists, biologists, and orthopaedic surgeons to determine the most suitable modifications on biomaterials to design favourable 3D scaffolds based on PCL for the targeted healing of damaged bone tissue.

Artificial Periosteum with Oriented Surface Nanotopography and High Tissue Adherent Property

Massive periosteal defects often significantly impair bone regeneration and repair, which have become a major clinical challenge. Unfortunately, current engineered periosteal materials can hardly currently focus on achieving high tissue adhesion property, being suitable for cell growth, and inducing cell orientation concurrently to meet the properties of nature periosteum. Additionally, the preparation of oriented surface nanotopography often relies on professional equipment. In this study, inspired by the oriented collagen structure of nature periosteum, we present a composite artificial periosteum with a layer of oriented nanotopography surface containing carbon nanotubes (CNTs), cross-linked with adhesive polydopamine (PDA) hydrogel on both terminals. An oriented surface structure that can simulate the oriented alignment of periosteal collagen fibers can be quickly and conveniently obtained via a simple stretching of the membrane in a water bath. With the help of CNTs, our artificial periosteum exhibits sufficient mechanical strength and desired oriented nanotopological structure surface, which further induces the directional arrangement of human bone marrow mesenchymal stem cells (hBMSCs) on the membrane. These oriented hBMSCs express significantly higher levels of osteogenic genes and proteins, while the resultant composite periosteum can be stably immobilized in vivo in the rat model of massive calvarial defect through the PDA hydrogel, which finally shows promising bone regeneration ability. We anticipate that the developed functional artificial periosteum has great potential in biomedical applications for the treatment of composite defects of the bone and periosteum.

Boron nitride nanofiber/Zn-doped hydroxyapatite/polycaprolactone scaffolds for bone tissue engineering applications

In this study, Zn doped hydroxyapatite (Zn HA)/boron nitride nanofiber (BNNF)/poly-ε-caprolactone (PCL) composite aligned fibrous scaffolds are produced with rotary jet spinning (RJS) for bone tissue engineering applications. It is hypothesized that addition of Zn HA and BNNF will contribute to cell viability as well as mechanical and osteogenic properties of the PCL scaffolds. Zn HA was synthesized by mixing Ca and P sources followed by sonication and aging whereas BNNF was obtained by the reaction of melamine with boric acid followed by freeze-drying for annealing of fibers. It is found that incorporation of both Zn HA and BNNF in PCL fibers resulted in higher calcium phosphate (CaP) precipitation on the scaffolds. Also, in vitro cell culture studies showed that presence of both Zn HA and BNNF also had synergistic effect for enhanced proliferation and osteogenic activity of Saos-2 cells. Mechanical properties of PCL-Zn HA-BNNF were found similar to that of non-load bearing bones. Furthermore, the presence of Zn HA and BNNF had synergistic effects to cell attachment, proliferation and spreading without causing cytotoxic effect on cells. The highest ALP activity was obtained in the PCL-Zn HA- BNNF group at days 7 and 14 due to release of zinc, calcium, phosphate and boron. Considering its mechanical and bioactivity properties, PCL-Zn HA-BNNF composite scaffolds hold promise as non-load bearing bone substitutes.

Novel In Situ-Cross-Linked Electrospun Gelatin/Hydroxyapatite Nonwoven Scaffolds Prove Suitable for Periodontal Tissue Engineering

Periodontal diseases affect millions of people worldwide and can result in tooth loss. Regenerative treatment options for clinical use are thus needed. We aimed at developing new nonwoven-based scaffolds for periodontal tissue engineering. Nonwovens of 16% gelatin/5% hydroxyapatite were produced by electrospinning and in situ glyoxal cross-linking. In a subset of scaffolds, additional porosity was incorporated via extractable polyethylene glycol fibers. Cell colonization and penetration by human mesenchymal stem cells (hMSCs), periodontal ligament fibroblasts (PDLFs), or cocultures of both were visualized by scanning electron microscopy and 4′,6-diamidin-2-phenylindole (DAPI) staining. Metabolic activity was assessed via Alamar Blue^® staining. Cell type and differentiation were analyzed by immunocytochemical staining of Oct4, osteopontin, and periostin. The electrospun nonwovens were efficiently populated by both hMSCs and PDLFs, while scaffolds with additional porosity harbored significantly more cells. The metabolic activity was higher for cocultures of hMSCs and PDLFs, or for PDLF-seeded scaffolds. Periostin and osteopontin expression was more pronounced in cocultures of hMSCs and PDLFs, whereas Oct4 staining was limited to hMSCs. These novel in situ-cross-linked electrospun nonwoven scaffolds allow for efficient adhesion and survival of hMSCs and PDLFs. Coordinated expression of differentiation markers was observed, which rendered this platform an interesting candidate for periodontal tissue engineering.