Research on the osteogenic properties of 3D-printed porous titanium alloy scaffolds loaded with Gelma/PAAM-ZOL composite hydrogels.

Although titanium alloy is the most widely used endoplant material in orthopedics, the material is bioinert and good bone integration is difficult to achieve. Zoledronic acid (ZOL) has been shown to locally inhibit osteoclast formation and prevent osteoporosis, but excessive concentrations of ZOL exert an inhibitory effect on osteoblasts; therefore, stable and controlled local release of ZOL may reshape bone balance and promote bone regeneration. To promote the adhesion of osteoblasts to many polar groups, researchers have applied gelatine methacryloyl (Gelma) combined with polyacrylamide hydrogel (PAAM), which significantly increased the hydrogen bonding force between the samples and improved the stability of the coating and drug release. A series of experiments demonstrated that the Gelma/PAAM-ZOL bioactive coating on the surface of the titanium alloy was successfully prepared. The coating can induce osteoclast apoptosis, promote osteoblast proliferation and differentiation, achieve dual regulation of bone regeneration, successfully disrupt the balance of bone remodelling and promote bone tissue regeneration. Additionally, the coating improves the metal biological inertness on the surface of titanium alloys and improves the bone integration of the scaffold, offering a new strategy for bone tissue engineering to promote bone technology.

Tricalcium Phosphate as a Bone Substitute to Treat Massive Acetabular Bone Defects in Hip Revision Surgery: A Systematic Review and Initial Clinical Experience with 11 Cases.

The use of tricalcium phosphate (TCP) as a bone substitute is gaining increasing interest to treat severe acetabular bone defects in revision total hip arthroplasty (rTHA). The aim of this study was to investigate the evidence regarding the efficacy of this material. A systematic review of the literature was performed according to the PRISMA and Cochrane guidelines. The study quality was assessed using the modified Coleman Methodology Score (mCMS) for all studies. A total of eight clinical studies (230 patients) were identified: six on TCP used as biphasic ceramics composed of TCP and hydroxyapatite (HA), and two as pure-phase ceramics consisting of TCP. The literature analysis showed eight retrospective case series, of which only two were comparative studies. The mCMS showed an overall poor methodology (mean score 39.5). While the number of studies and their methodology are still limited, the available evidence suggests safety and overall promising results. A total of 11 cases that underwent rTHA with a pure-phase ceramic presented satisfactory clinical and radiological outcomes at initial short-term follow-up. Further studies at long-term follow-up, involving a larger number of patients, are needed before drawing more definitive conclusions on the potential of TCP for the treatment of patients who undergo rTHA.

Naringin Release from a Nano-Hydroxyapatite/Collagen Scaffold Promotes Osteogenesis and Bone Tissue Reconstruction.

Bone fractures and defects are a major health issue and have reportedly affected over 455 million individuals globally to date. Bone tissue engineering has gained great success in bone defect repair and bone reconstruction based on the use of nano-hydroxyapatite (nHA) or collagen (COL). Both nHA and COL exhibit osteogenic induction capacity to support bone tissue regeneration; however, the former suffers from poor flexibility and the latter lacks mechanical strength. Biological scaffolds created by combining nHA and COL (nHA/COL) can overcome the drawbacks imposed by individual materials and, therefore, have become widely applied in tissue engineering. The composite scaffolds can further promote tissue reconstruction by allowing the loading of various growth factors. Naringin (NG) is a natural flavonoid. Its molecular weight is 580.53 Da, lower than that of many growth factors, and it causes minimal immune responses when being introduced in vivo. In addition, naringin is safe, non-toxic, inexpensive to produce, and has superior bio-properties. In this study, we introduced NG into a nHA/COL scaffold (NG/nHA/COL) and exploited the potentials of the NG/nHA/COL scaffold in enhancing bone tissue regeneration. NG/nHA/COL scaffolds were fabricated by firstly combining nHA and collagen at different compositional ratios, followed by NG encapsulation. NG release tests showed that the scaffold with a nHA/COL mass ratio of 7:3 exhibited the optimal property. The in vitro cell study showed the desirable biocompatibility of the NG/nHA/COL scaffold, and its effective promotion for the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), as proved by an increased alkaline phosphatase (ALP) activity, the formation of more calcium nodules, and a higher expression of osteogenic-related genes involving Osteocalcin (OCN), BMP-2, and Osteopontin (OPN), compared with the control and nHA/COL groups. When administered into rats with skull defects, the NG/nHA/COL scaffold significantly promoted the reconstruction of bone tissues and the early repair of skull defects, indicating the great potential of NG/nHA/COL scaffolds in bone tissue engineering.

Osteogenic growth peptide (OGP)-loaded amphiphilic peptide (NapFFY) supramolecular hydrogel promotes osteogenesis and bone tissue reconstruction.

Efficient bone reconstruction after bone injury remains a great challenge. Injectable supramolecular hydrogels based on amphiphilic peptide have been widely used due to their good biocompatability, non-immunogenicity, and manipulable physicochemical properties by sequence design. Herein, we used a well-studied hydrogelator, NapFFY, to coassemble with osteogenic growth peptide (OGP) to prepare a supramolecular hydrogel, NapFFY-OGP. Both in vitro and in vivo studies demonstrate that OGP was ideally synchronously, and continuously released from the hydrogel to effectively promote the regeneration and reconstruction of skull bone defects. More specifically, after the embedding the rat skull defect area with NapFFY-OGP hydrogels, a bone regeneration rate of 37.54% bone volume fraction (BV/TV) was achieved compared to that of NapFFY hydrogel group (25.09%). NapFFY-OGP hydrogel shows great promise in the clinic repair of bone defects in the future.