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Although attempts have been made to immobilize dual short peptides on a biomaterial surface, the optimization, characterization and functional analysis of the peptide immobilization onto poly(buthylene succinate)/β-tricalcium phosphate (PBSu/TCP) composites have not yet been reported. The present study was, therefore, carried out to optimize and characterize the dual immobilization of type I collagen short peptide (COLsp) and bone morphogenetic protein-2 short peptide (BMP-2sp) onto hydrolyzed PBSu/TCP (HPBSu/TCP) composites, and the bioactivity of the resulting dual peptide-immobilized surfaces was also determined in vitro. The results demonstrated that sequential immobilization of the dual short peptides was successfully established. Each of the peptides was chemically bound to the 1.5 M NaOH-treated composite (with the PBSu to TCP weight ratio of 60:40) (HPBSu/TCP-6040–1.5); bright red fluorescence of COLsp (25 µM) and vividly green fluorescence of BMP-2sp (50 µM) were individually observed explicitly on the dual peptide-immobilized material. As a result, the HPBSu/TCP-6040–1.5 composite film conjugated with both 25 µM Col I and 50 µM BMP-2 was examined for its osteogenic efficacy. The results showed that COLsp/BMP-2sp-immobilized HPBSu/TCP composite significantly enhanced hMSC proliferation as well as osteoblast differentiation of hMSCs under osteogenic induction. Most importantly, COLsp/BMP-2sp-immobilized HPBSu/TCP composite induced biomineralization in the absence of any additional osteogenic stimulus. The present study has successfully demonstrated the sequential immobilization of the dual short peptides, i.e., COLsp and BMP-2sp, on HPBSu/TCP surface, with each short peptide being chemically bound to the hydrolyzed composite surface. The COLsp/BMP-2sp-immobilized HPBSu/TCP film possessed the bioactivities of the respective full-length proteins by stimulating hMSC proliferation, osteoblast differentiation and, most importantly, mineralization without the requirement of exogenous osteogenic supplements. This suggests highly improved performance of the biologically responsive HPBSu/TCP composite and thus its potential use in bone tissue engineering. [ABSTRACT FROM AUTHOR]

Long-term clinical success of a titanium implant not only depends upon osseointegration between implant and bone surface but also on the response of host immune cells. Following implantation of biomaterials, an inflammatory response, including T lymphocyte response, is ostensibly initiated by implant-cell interaction. However, little is known about the responses of T lymphocytes to titanium dioxide nanotubes. The present study aimed to explore the effect of titanium dioxide nanotubes on T lymphocytes in vitro and its biological consequences. The results of the present study showed that titanium dioxide nanotubes with diameter of 30–105 nm were non-cytotoxic to T lymphocytes, and the 105 nm titanium dioxide nanotube surface specifically possessed an ability to activate T lymphocytes, thus increasing DNA synthesis and cell proliferation. In addition, the 105 nm titanium dioxide nanotubes significantly activated the expression of FGF-2 gene and protein in T lymphocytes although smaller nanotubes (i.e. those with diameters of approximately 30 and 70 nm) had little effect on this. The present study investigated the mechanism by which 105 nm nanotubes stimulated FGF-2 expression in T lymphocytes by blocking key MAPK pathways. The inhibitors of JNK1/2/3 and ERK1/2 significantly inhibited 105 nm titanium dioxide nanotubes-induced FGF-2 expression. Corresponding to the increased expression of FGF-2, only the supernatant from T lymphocytes cultured on 105 nm nanotubes stimulated human mesenchymal stem cell proliferation. FGF-2 blocking antibody partially reversed the increased proliferation of human mesenchymal stem cells, supporting the role of T lymphocyte-derived FGF-2 in enhanced human mesenchymal stem cell proliferation. This suggests a significant role of T lymphocyte-titanium dioxide nanotube interaction in the proliferation of human mesenchymal stem cells, which is pivotal to the formation of new bone following implant placement. [ABSTRACT FROM AUTHOR]

Bone substitute is a therapeutic approach to treat bone abnormalities. A scaffold serves mainly as osteoconductive elements. To facilitate a better biological performance, short collagen peptide was immobilized onto hydrolyzed poly(butylene succinate)/β-tricalcium phosphate (HPBSu/TCP) scaffolds. PBSu/TCP (80:20) scaffolds were fabricated by a supercritical CO2 technique, hydrolyzed with 0.6 M NaOH and conjugated with short collagen peptide tagged with or without red fluorescence. The surface morphology and porous structure of scaffolds were characterized by scanning electron microscopy and micro-computed tomography. Human mesenchymal stem cells were cultured onto the scaffolds and examined for osteogenic differentiation and biomineralization in vitro by means of alkaline phosphatase activity, alizarin red staining, and reverse transcription-polymerase chain reaction. The PBSu/TCP and HPBSu/TCP scaffolds were successfully prepared. Scanning electron microscopy and micro-computed tomography results showed that the porosity was distributed throughout the scaffolds with the pore sizes in the range of 250–900 µm. Fluorescence microscopy demonstrated retention of tagged short collagen peptide on the scaffold. Mesenchymal stem cells adhered and grew well on the material. Under osteogenic induction, cells cultured on the short collagen peptide -immobilized scaffold significantly produced a greater amount of alkaline phosphatase activity and positive mineralization than those cultured on the control scaffold. The present results have shown that the short collagen peptide-immobilized HPBSu/TCP scaffold enhanced osteoinduction and biomineralization of stem cell-derived osteoblasts, possibly via stimulation of alkaline phosphatase activity. This suggests the potential use of osteogenic peptide-immobilized material in bone tissue engineering for correcting bone defects. [ABSTRACT FROM AUTHOR]

Although poly(butylene succinate)/β-tricalcium phosphate (PBSu/TCP) composites are biocompatible and allow the growth and osteogenic differentiation of stem cells, cell attachment and adhesion to the PBSu-based substrates is often limited. To enhance cell adhesion and proliferation, we used a sodium hydroxide (NaOH) hydrolysis technique to generate a different degree of roughness on PBSu/TCP substrates with different PBSu:TCP ratios. The results showed that NaOH hydrolysis increased surface roughness of PBSu/TCP substrates in a concentration-dependent manner. Substrates with higher ratios of TCP:PBSu provided more porous topography after NaOH hydrolysis, with a substrate containing 40 wt % TCP (PBSu/TCP-6040) hydrolyzed with 1.5 M NaOH (HPBSu/TCP-6040-1.5) showing the highest degree of roughness. As with the roughness, PBSu/TCP surface hydrophilicity was positively affected by the increasing NaOH concentration and TCP incorporation. Stem cells adhered best on HPBSu/TCP-6040-1.5 with three-dimensionally elongated cell extensions. Moreover, the HPBSu/TCP-6040-1.5 substrate most significantly facilitated stem cell actin cytoskeleton reorganization and vinculin-positive focal adhesion formation when compared with the other substrates tested. HPBSu/TCP-6040-1.5 also demonstrated the greatest increase in cell proliferation when compared with the other substrates studied. In conclusion, the results have shown that among various substrates tested, HPBSu/TCP-6040-1.5 provided the best support for stem cell adhesion and proliferation, suggesting its potential use in bone engineering. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 658-670, 2015. [ABSTRACT FROM AUTHOR]

Bone tissue engineering offers the prospect of alternative therapies for clinically relevant skeletal defects. Poly(butylene succinate) (PBSu) is a biodegradable and biocompatible polyester which possesses some unfavorable biomaterial properties. In order to improve this limitation, we developed PBSu/hydroxyapatite (HA) and PBSu/β-tricalcium phosphate (TCP) composites to support the growth and osteogenic differentiation of human mesenchymal stem cells (hMSCs). The results showed that phase separation morphology of the composites were detected in both PBSu/HA and PBSu/TCP films where calcium phosphate (HA and TCP) dispersed thoroughly into PBSu. The addition of either HA or TCP increased the hydrophilicity of the resulting composites. All the materials appeared to be biocompatible and supportedin vitrogrowth and osteoblast differentiation of hMSCs. In conclusion, the currently developed composite materials possess good biocompatibility and allow the growth and osteogenic differentiation of hMSCsin vitro, suggesting their potential application in stem cell-based bone engineering. [ABSTRACT FROM PUBLISHER]

Bone engineering is a promising therapeutic approach to correct skeletal defects, and genetically-modified stem cells have been implicated in engineering new bone. However, the use of genetically-modified human mesenchymal stem cells targeting an osteogenic growth factor Wnt is not yet investigated. In the present study, a proliferation assay and the alkaline phosphatase (ALP) activity and expression of runt-related transcription factor 2 (Runx2) and osteocalcin (OC) transcripts were investigated to examine the effect of Wnt2 overexpression, Wnt3a overexpression, and Wnt9a knockdown on cell proliferation and osteoblast differentiation of bone marrowderived mesenchymal stem cells (BMSCs). The results showed that the expression of Wnt2 and Wnt3a was up-regulated throughout the osteoblast differentiation period of BMSCs, whereas that of Wnt9a was down-regulated. Overexpression of Wnt3a stimulated cell proliferation while knockdown of Wnt9a increased the ALP activity and the expression of Runx2 and OC. Double transfection producing Wnt3a overexpression and Wnt9a knockdown simultaneously resulted in up-regulation of osteoblast differentiation markers, i.e., the ALP activity and the Runx2 expression. In conclusion, simultaneous genetic modification of Wnt3a overexpression and Wnt9a knockdown enhances osteoblast differentiation of BMSCs, suggesting its osteogenic potency to regenerate new bone in vivo. [ABSTRACT FROM AUTHOR]

The increasing number of elderly people across the globe has led to a rise in osteoporosis and bone fractures, significantly impacting the quality of life and posing substantial health and economic burdens. Despite the development of tissue-engineered bone constructs and stem cell-based therapies to address these challenges, their efficacy is compromised by inadequate vascularization and innervation during bone repair. Innervation plays a pivotal role in tissue regeneration, including bone repair, and various techniques have been developed to fabricate innervated bone scaffolds for clinical use. Incorporating neural-related cells and delivering neurotrophic factors are emerging strategies to accelerate bone regeneration through innervation. However, research into neurogenic cell sources remains limited. Meanwhile, neural stem/progenitor cells (NSPCs) are emerging as promising cells for treating neurodegenerative disorders and spinal cord injuries due to their multifunctional capacity in promoting angiogenesis, neurogenesis, and immunomodulation, making them promising candidates for achieving innervation in bone substitutes. In this review, we discuss the regenerative potential of NSPCs in tissue regeneration. We propose their feasibility for bone therapy through their secreted exosomes during traumatic brain injury, contributing to the acceleration of bone healing. Additionally, we discuss the essential neurotrophic factors released from NSPCs and their osteogenic properties. This review emphasizes the necessity for further investigation of the role of NSPCs in bone regeneration.

This investigation developed new composite bone cements using urethane dimethacrylate (UDMA), poly(propylene glycol) dimethacrylate (PPGDMA), and hydroxyethyl methacrylate (HEMA), with micrometer-sized aluminosilicate glass filler. Monocalcium phosphate monohydrate (MCPM) and hydroxyapatite (HA) particles were added to enhance biological performance, particularly osteo-immunomodulation. Free radical polymerization was triggered by mixing two pastes containing either benzoyl peroxide (BPO, an initiator) or N-tolyglycine glycidyl methacrylate (NTGGMA, an activator). Increasing butylated hydroxytoluene (BHT, an inhibitor) enabled a suitable delay after mixing at 25 °C for placement. At 37 °C, the delay time was reduced and the final conversion was enhanced. Findings also demonstrated the biocompatibility of the developed bone cement toward osteo-immunological cell lineages, including mesenchymal stem cells (MSCs), fibroblasts, osteoclast precursor RAW 246.7 cells, and peripheral blood mononuclear cells (PBMCs). Notably, the cement with both MCPM and HA combined facilitated sufficient MSC growth, enabling subsequent mineralization while concurrently suppressing the proliferation of fibroblasts, osteoclast progenitors, and PBMCs. Furthermore, composite cement exhibited the capacity to differentially regulate osteoblast differentiation, cell-(in)dependent mineralization, osteoclastogenesis, and PBMC-mediated inflammatory responses at both cellular and molecular levels in vitro. These observations suggested their potential use for bone repair, especially in cases of inflammation-associated bone defects., Competing Interests: The authors declare the following competing financial interest(s): The work is covered by the following licensed patent families: Formulations and composites with bioactive fillers (US8252851 B2, EP2066703B1, US20100069469, WO2008037991A1). This may be considered a conflict of interest as in the future the corresponding author (A.Y.) may receive royalties when a commercial product is produced., (© 2024 The Authors. Published by American Chemical Society.)

Background: Polybutylene succinate (PBSu) and PBSu/β-tricalcium phosphate (TCP) composites are biocompatible and good candidates as bone graft materials. However, little is known about the responses of T lymphocytes to these biomaterials, which play an important role in the success of bone grafting., Methods: Activated T lymphocytes were cultured onto 32 mm diameter films (PBSu/TCP films), that had previously been placed in 6-well culture plates, for 8, 24 and 72 hours. A plastic-well culture plate was used as a control surface. The effects of PBSu-based biomaterials on T lymphocytes were examined by the using flow cytometry and reverse-transcription polymerase chain reaction., Results: These biomaterials were non-toxic to T lymphocytes, allowing their normal DNA synthesis and activation. All materials induced only transient activation of T lymphocytes, which existed no longer than 72 hours. Proportions of four main CD4/CD8 T lymphocyte subpopulations were not affected by these biomaterials. Moreover, PBSu and PBSu/TCP significantly suppressed the expression of IL-1β and IL-6 genes by 15-35% and 21-26%, respectively. In contrast, a PBSu/TCP composite (at PBSu:TCP=60:40) significantly stimulated the expression of IL-10 and IL-13 genes by 17% and 19%, respectively., Conclusions: PBSu and PBSu/TCP composites were non-toxic to T lymphocytes and did not induce unfavorable responses of T lymphocytes. The tested biomaterials down-regulated key proinflammatory cytokine genes and up-regulated anti-inflammatory cytokine genes in T lymphocytes. These suggest that the biomaterials studied are good candidates as bone graft materials.