Preparation of porous PLA/DBM composite biomaterials and experimental research of repair rabbit radius segmental bone defect

3D-Printed Piezoelectric Scaffolds with Shape Memory Polymer for Bone Regeneration

The application of piezoelectric nanoparticles with shape memory polymer (SMP) to 3D-printed piezoelectric scaffolds for bone defect repair is an attractive research direction. However, there is a significant difference in dielectric constants between the piezoelectric phase and polymer phase, limiting the piezoelectric property. Therefore, novel piezoelectric acrylate epoxidized soybean oil (AESO) scaffolds doped with piezoelectric Ag-TMSPM-pBT (ATP) nanoparticles (AESO-ATP scaffolds) are prepared via digital light procession 3D-printing. The Ag-TMSPM-pBT nanoparticles improve the piezoelectric properties of the AESO scaffolds by TMSPM covalent functionalization and conductive Ag nanoparticles. The AESO scaffolds doped with 10 wt% Ag-TMSPM-pBT nanoparticles (AESO-10ATP scaffolds) exhibit promising piezoelectrical properties, with a piezoelectric coefficient (d33) of 0.9 pC N-1 and an output current of 146.4 nA, which are close to the piezoelectric constants of bone tissue. In addition, these scaffolds exhibit good shape memory function and can quickly recover their original shape under near-infrared (NIR) light irradiation. The results of osteogenesis capability evaluation indicate that the AESO-10ATP scaffolds can promote osteogenic differentiation of BMSCs in vitro and bone defect repair in vivo, indicating the 3D-printed AESO-10ATP piezoelectric scaffolds may have great application potential for bone regeneration.

Recent developments in biomaterials for long-bone segmental defect reconstruction: A narrative overview

Reconstruction of long-bone segmental defects (LBSDs) has been one of the biggest challenges in orthopaedics. Biomaterials for the reconstruction are required to be strong, osteoinductive, osteoconductive, and allowing for fast angiogenesis, without causing any immune rejection or disease transmission. There are four main types of biomaterials including autograft, allograft, artificial material, and tissue-engineered bone. Remarkable progress has been made in LBSD reconstruction biomaterials in the last ten years.

The translational potential of this article

Our aim is to summarize recent developments in the divided four biomaterials utilized in the LBSD reconstruction to provide the clinicians with new information and comprehension from the biomaterial point of view.

Preparation of poly(lactic acid)/sintered hydroxyapatite composite biomaterial by supercritical CO2

Based on a kind of sintered hydroxyapatite (HA) with a good cytocompatibility, a series of polylactic acid (PLA) and PLA/HA with the various PLA:HA weight ratio (5:5, 4:6, 3:7, 2:8, 1:9) were fabricated by supercritical CO2. The physical and chemical properties were evaluated by pH, degradation, water absorption, porosity, density, mechanical property, and cytotoxicity respectively. With the increase of HA content, the pH value and porosity increased gradually, while weight loss rate and the density showed a gradual downward trend. Existence of HA can drastically improve the hydroscopicity of PLA scaffolds. The compression strength values slightly increased (p>0.05) from 39.96 MPa of PLA to 45.00 MPa of PLA/HA with the ratio of 7:3, subsequently, the values decreased (p<0.05) from 43.29 MPa (8:2) to 19.00 MPa (9:1). While the modulus of elasticity decreased (p<0.05) from 5.89 to 1.84 GPa with increasing HA content. The PLA/HA (8:2) promoted cell proliferation more significantly than any of other groups (p<0.05). Based on the results, the overall properties of porous scaffolds are the optimal when the weight ratio of PLA/HA is 8:2. Its pH, porosity, density, compression strength, and elasticity modulus are 7.39, 83.0%, 0.60g/cm-3, 34.1 MPa and 2.63 GPa, respectively. SEM observation presented a homogeneous distribution of HA in PLA matrix and a foam-like structure comprising interconnected pores.

In Vitro and In Vivo (Rabbit, Guinea Pig, Mouse) Properties of a Novel Resorbable Polymer and Allogenic Bone Composite for Guided Bone Regeneration and Orthopedic Implants

INTRODUCTION

Currently, there is no bone fixation material that could be fully replaced by the competent recipient bone. The creeping substitution of the bone graft by the recipient bone is the result of its unique potential related to the presence of bone morphogenetic proteins (BMPs). However, the size of the human bone limits the use of allogenic implants for surgical (orthopedic) fixation. The aim of this project was to develop a novel composite material for guided bone regeneration, consisting of human bone powder obtained from a tissue bank and a resorbable polymer (13 wt% of bone powder in a medical poly-l-lactide polymer). Such a biomaterial could possess osteoinductive properties and be used to manufacture bone fixation implants of different shapes and sizes.

MATERIALS AND METHODS

The samples were obtained by tape casting and foils pressing, and subsequently radiation sterilized with a dose of 35 kGy. Two cell lines-normal mouse embryo fibroblasts (Balb 3T3/c) and human fetal osteoblasts (hFOB 1.19)-were cultured with the extracts of the biomaterials (MTT assay) or in indirect contact with the evaluated biomaterials (agar diffusion method). In addition, cell viability was evaluated after 5 days of incubation with biomaterial using ThinCert tissue culture inserts. Then, the following in vivo examinations were conducted: acute systemic toxicity, skin irritation and sensitization, and local effects after implantation.

RESULTS

The evaluated composite material showed a high degree of cytocompatibility and biocompatibility according to the International Standards.

CONCLUSIONS

The preclinical evaluation we performed on the new, polylactide-based allogenic biomaterial opens up possibilities to patent pending and advanced in vivo testing.

Preparation and characterization of cockle shell aragonite nanocomposite porous 3D scaffolds for bone repair

The demands for applicable tissue-engineered scaffolds that can be used to repair load-bearing segmental bone defects (SBDs) is vital and in increasing demand. In this study, seven different combinations of 3 dimensional (3D) novel nanocomposite porous structured scaffolds were fabricated to rebuild SBDs using an extraordinary blend of cockle shells (CaCo₃) nanoparticles (CCN), gelatin, dextran and dextrin to structure an ideal bone scaffold with adequate degradation rate using the Freeze Drying Method (FDM) and labeled as 5211, 5400, 6211, 6300, 7101, 7200 and 8100. The micron sized cockle shells powder obtained (75 µm) was made into nanoparticles using mechano-chemical, top-down method of nanoparticles synthesis with the presence of the surfactant BS-12 (dodecyl dimethyl bataine). The phase purity and crystallographic structures, the chemical functionality and the thermal characterization of the scaffolds’ powder were recognized using X-Ray Diffractometer (XRD), Fourier transform infrared (FTIR) spectrophotometer and Differential Scanning Calorimetry (DSC) respectively. Characterizations of the scaffolds were assessed by Scanning Electron Microscopy (SEM), Degradation Manner, Water Absorption Test, Swelling Test, Mechanical Test and Porosity Test. Top-down method produced cockle shell nanoparticles having averagely range 37.8±3–55.2±9 nm in size, which were determined using Transmission Electron Microscope (TEM). A mainly aragonite form of calcium carbonate was identified in both XRD and FTIR for all scaffolds, while the melting (Tm) and transition (Tg) temperatures were identified using DSC with the range of Tm 62.4–75.5 °C and of Tg 230.6–232.5 °C. The newly prepared scaffolds were with the following characteristics: (i) good biocompatibility and biodegradability, (ii) appropriate surface chemistry and (iii) highly porous, with interconnected pore network. Engineering analyses showed that scaffold 5211 possessed 3D interconnected homogenous porous structure with a porosity of about 49%, pore sizes ranging from 8.97 to 337 µm, mechanical strength 20.3 MPa, Young's Modulus 271±63 MPa and enzymatic degradation rate 22.7 within 14 days.

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An innovative mixture of nano-CaCo₃ (aragonite), gelatin, dextrin and dextran.

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Scaffold 5211 reached a tipping point in terms of ideal morphology, optimal physiochemical properties, and great mechanical strength.

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Scaffold 5211 may guarantee the achievement of the developed scaffold purposes in true biological system.

Stem cells, growth factors and scaffolds in craniofacial regenerative medicine

Current reconstructive approaches to large craniofacial skeletal defects are often complicated and challenging. Critical-sized defects are unable to heal via natural regenerative processes and require surgical intervention, traditionally involving autologous bone (mainly in the form of nonvascularized grafts) or alloplasts. Autologous bone grafts remain the gold standard of care in spite of the associated risk of donor site morbidity. Tissue engineering approaches represent a promising alternative that would serve to facilitate bone regeneration even in large craniofacial skeletal defects. This strategy has been tested in a myriad of iterations by utilizing a variety of osteoconductive scaffold materials, osteoblastic stem cells, as well as osteoinductive growth factors and small molecules. One of the major challenges facing tissue engineers is creating a scaffold fulfilling the properties necessary for controlled bone regeneration. These properties include osteoconduction, osetoinduction, biocompatibility, biodegradability, vascularization, and progenitor cell retention. This review will provide an overview of how optimization of the aforementioned scaffold parameters facilitates bone regenerative capabilities as well as a discussion of common osteoconductive scaffold materials.

Polylactic Acid Based Nanocomposites: Promising Safe and Biodegradable Materials in Biomedical Field

Polylactic acid (PLA) is widely used in biological areas due to its excellent compatibility, bioabsorbability, and degradation behavior in human bodies. Pure polylactic acid has difficulty in meeting all the requirements that specific field may demand. Therefore, PLA based nanocomposites are extensively investigated over the past few decades. PLA based nanocomposites include PLA based copolymers in nanometer size and nanocomposites with PLA or PLA copolymers as matrix and nanofillers as annexing agent. The small scale effect and surface effect of nanomaterials help improve the properties of PLA and make PLA based nanocomposites more popular compared with pure PLA materials. This review mainly introduces different kinds of PLA based nanocomposites in recent researches that have great potential to be used in biomedical fields including bone substitute and repair, tissue engineering, and drug delivery system.