Fabrication and characterization of three-dimensional poly(lactic acid-co-glycolic acid), atelocollagen, and fibrin bioscaffold composite for intervertebral disk tissue engineering application

The use of synthetically derived poly(lactic- co-glycolic acid) scaffold and naturally derived materials in regeneration of intervertebral disks has been reported in many previous studies. However, the potential effect of poly(lactic- co-glycolic acid) in combination with atelocollagen or fibrin or both atelocollagen and fibrin bioscaffold composite have not been mentioned so far. This study aims to fabricate and characterize three-dimensional poly(lactic- co-glycolic acid) scaffold incorporated with (1) atelocollagen, (2) fibrin, and (3) both atelocollagen and fibrin combination for intervertebral disk tissue engineering application. The poly(lactic- co-glycolic acid) without any natural, bioscaffold composites was used as control. The chemical conformation, morphology, cell–scaffold attachment, porosity, water uptake capacity, thermal properties, mechanical strength, and pH level were evaluated on all scaffolds using attenuated total reflectance Fourier transform infrared, scanning electron microscope, gravimetric analysis, swelling test, differential scanning calorimetry, and Instron E3000, respectively. Biocompatibility test was conducted to assess the intervertebral disk, annulus fibrosus cells viability using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The attenuated total reflectance Fourier transform infrared results demonstrated notable peaks of amide bond suggesting interaction of atelocollagen, fibrin, and both atelocollagen and fibrin combination into the poly(lactic- co-glycolic acid) scaffold. Based on the scanning electron microscope observation, the pore size of the poly(lactic- co-glycolic acid) structure significantly reduced when it was incorporated with atelocollagen and fibrin. The poly(lactic- co-glycolic acid)–atelocollagen scaffolds demonstrated higher significant swelling ratios, mechanical strength, and thermal stability than the poly(lactic- co-glycolic acid) scaffold alone. All the three bioscaffold composite groups exhibited the ability to reduce the acidic poly(lactic- co-glycolic acid) by-product. In this study, the biocompatibility assessment using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cells proliferation assay demonstrated a significantly higher annulus fibrosus cells viability in poly(lactic- co-glycolic acid)–atelocollagen–fibrin compared to poly(lactic- co-glycolic acid) alone. The cellular attachment is comparable in poly(lactic- co-glycolic acid)–atelocollagen–fibrin and poly(lactic- co-glycolic acid)–fibrin scaffolds. Overall, these results may suggest potential use of poly(lactic- co-glycolic acid) combined with atelocollagen and fibrin bioscaffold composite for intervertebral disk regeneration.

ADVANCED 3D RAPID PROTOTYPING BIOMODELING TECHNIQUE FOR KNEE SURGERY

Advanced three-dimensional (3D) models have played more and more essential roles in orthopedics surgical interventions. In order to improve the clinical outcomes of knee surgery (KS) including minimally invasive knee surgery (MIKS), the melted extrusion modeling (MEM), a rapid prototyping (RP) technique, was used efficiently to fabricate real life-size 3D physical models of interesting knees. The applications and advantages of the tangible RP-constructed 3D models in KS were elucidated in this study. As a result, better preparation including optimal preoperative planning was made so that KS could be performed in an accurate, safe and fast manner for each case. Besides, the surgical skills of MIKS were substantially improved. Therefore, the results suggest that KS can benefit much from the advanced 3D modeling technique.

Effect of Local Sustainable Release of BMP2-VEGF from Nano-Cellulose Loaded in Sponge Biphasic Calcium Phosphate on Bone Regeneration

Bone regeneration is a coordinated process mainly regulated by multiple growth factors. Vascular endothelial growth factor (VEGF) stimulates angiogenesis and bone morphogenetic proteins (BMPs) induce osteogenesis during bone healing process. The aim of this study was to investigate how these growth factors released locally and sustainably from nano-cellulose (NC) simultaneously effect bone formation. A biphasic calcium phosphate (BCP)-NC-BMP2-VEGF (BNBV) scaffold was fabricated for this purpose. The sponge BCP scaffold was prepared by replica method and then loaded with 0.5% NC containing BMP2-VEGF. Growth factors were released from NC in a sustainable manner from 1 to 30 days. BNBV scaffolds showed higher cell attachment and proliferation behavior than the other scaffolds loaded with single growth factors. Bare BCP scaffolds and BNBV scaffolds seeded with rat bone marrow mesenchymal stem cells were implanted ectopically and orthotopically in nude mice for 4 weeks. No typical bone formation was exhibited in BNBV scaffolds in ectopic sites. BMP2 and VEGF showed positive effects on new bone formation in BNBV scaffolds, with and without seeded stem cells, in the orthotopic defects. This study demonstrated that the BNBV scaffold could be beneficial for improved bone regeneration. Stem cell incorporation into this scaffold could further enhance the bone healing process.

Fabrication aspects of PLA-CaP/PLGA-CaP composites for orthopedic applications: a review

For several decades, composites made of polylactic acid-calcium phosphates (PLA-CaP) and polylactic acid-co-glycolic acid-calcium phosphates (PLGA-CaP) have seen widespread uses in orthopedic applications. This paper reviews the fabrication aspects of these composites, following the ubiquitous materials science approach by studying "processing-structure-property" correlations. Various fabrication processes such as microencapsulation, phase separation, electrospinning, supercritical gas foaming, etc., are reviewed, with specific examples of their applications in fabricating these composites. The effect of the incorporation of CaP materials on the mechanical and biological performance of PLA/PLGA is addressed. In addition, this paper describes the state of the art on challenges and innovations concerning CaP dispersion, incorporation of biomolecules/stem cells and long-term degradation of the composites.

Nano-hydroxyapatite/chitosan sponge-like biocomposite for repairing of rat calvarial critical-sized bone defect

A three-dimensional porous nano-hydroxyapatite (nHA)/chitosan (CS) biocomposite was synthesized. The rod-like nHA grains of 15—30 × 5—10 nm in size were observed by TEM and confirmed by characteristic XRD patterns. The diameters of the interconnecting pores of the nHA/CS biocomposite, determined by SEM, were 120—300 μm. Standard critical-sized calvarial bone defect ( = 6.5 mm) was created in Sprague-Dawley (SD) rats. In group 1, nHA/CS was implanted and in group 2, no implant was made in the defect. After 1 week, the histological assessment of group 1 clearly showed that a large number of living cells were anchored in the pores of the nHA/CS implants. New bone formation, both at the edge and in the center of implants, was found as early as 2 weeks. Histological assays confirmed that the newly formed bone tissue was bioactive and neovascularized. After 5 weeks, the mineral content and volume of the newly formed bone tissue in the defects were significantly greater in group 1 than in group 2 (p < 0.01). These results indicate that implantation of the nHA/CS enhanced the repair of bone defect and confirm the potential of this biocomposite as a bioactive bone grafting substitute.

Rapid anti-tumor effects of gelatin sponge/nano-β-TCP construct on SKOV-3 human ovarian cancer cells in vitro

Nanosized β-tricalcium phosphate (nano-β-TCP) particles were synthesized and characterized by transmission electron microscopy and X-ray diffraction. A surface coating was used to fabricate a medical absorbable gelatin sponge (GS) with nano-β-TCP biocomposite (GSN). The nano-β-TCP particles were ~150 nm in diameter and GSN was highly porous with pore diameter of ~200 μm. Modification via nano-β-TCP coating endowed the biocomposite with actual inhibitory effects on human ovarian cancer SKOV-3 cells. The systematic in vitro evaluations including ultrastructural observation, MTT assay, cell cycle analysis, apoptosis detection, and assessment of proliferating cell nuclear antigen (PCNA) expression data confirm that rapid internalization of nano-β-TCP, cell growth inhibition, G1/S phase cell cycle arrest, apoptosis, and suppression of PCNA expression play important roles in the rapid anti-tumor effects of GNS on SKOV-3 cells. Currently, in vitro and in vivo research work are in progress, including special anti-neoplastic drug delivery and synergistic effects of GSN and chemotherapeutic agents.

A 6-month in vivo study of polymer/mesenchymal stem cell constructs for cranial defects

Two biodegradable polymers, poly(L-lactide) and poly(ε-caprolactone) were blended (50/50) and used to produce polymeric scaffolds by the dual porogen approach using a salt leaching technique to create pores within the matrix, while supercritical-CO 2 treatment was used to enhance the interconnectivity and to remove impurities from synthesis steps. The scaffolds were highly porous (porosity >90%) with interconnected pore morphologies. These biodegradable scaffolds were evaluated in Sprague Dawley rats for osteoconductive properties over a 6-month period. Bone specimens were analyzed after 1, 3, and 6 months, for bone healing and tissue response. The cortical bone remodeling by controlled osteoblastic and osteoclastic activities as well as the bone marrow elements recovery were semi-quantitatively examined for each group. Excellent integration and biocompatibility behavior was observed in all groups. No adverse tissue responses were observed.

Multilevel Posterior Lumbar Interlaminar Fusion in Rabbits Using Bovine Bone Protein Extract Delivered by a RP-synthesized 3D Biopolymer Construct

Rapid prototyping (RP)-based highly porous poly(DL-lactic-co-glycolic acid)/tricalcium phosphate (PLGA/TCP(RP)) scaffolds were fabricated. PLGA/TCP constructs (PLGA/TCP(TS)) were also made via thermally induced phase separation with solvent casting and by particulate leaching approach. Both scaffolds were loaded with bovine bone protein extract (BBPE). Sixty-four New Zealand white rabbits were randomized into four groups (groups of A, B, C, and D) and unilaterally underwent posterior lumbar interlaminar fusion at L2—L4 level. Spinal fusions were systematically evaluated. In groups of A (PLGA/TCP (RP)/BBPE constructs) and C (autogenous iliac bone grafts), good bone fusions occurred in vivo. Histological analyses indicated that endochondral ossification played an essential role in initiation of bone fusions in group A, whereas in group B (PLGA/TCP(TS)/BBPE constructs), few bone fusions were observed. In group D (PLGA/TCP(RP) scaffolds alone), the scaffolds were biocompatible and biodegradable; however, no newly formed bone mass or bone fusion was found. Twelve weeks after surgery, the fusion was significantly higher in groups of A and C compared with groups B and D (p<0.01). The PLGA/ TCP(RP)/BBPE biomaterials have potential as grafting substitutes for bone healing and spinal fusion.

In Vitro and In Vivo Behaviors of the Three-layered Nanocarbonated Hydroxyapatite/Collagen/PLGA Composite

A three-layered nano-carbonated hydroxyapatite/collagen/poly (lactic-co-glycolic acid) (nCHAC/PLGA) composite membrane that consisted of 8 wt% nCHAC + PLGA/4 wt%nCHAC + PLGA/PLGA was developed using a layer-by-layer casting. The human periodontal ligament and osteoblastic MC3T3-E1 cells were cultured on the three-layered composite membrane; the co-culture gave a more positive response than the pure PLGA membrane. Subsequently, the composite and pure PLGA membranes were implanted into critical 6.2 mm defects in rat crania. After 4 weeks, significant healing was observed in the defects implanted with the nCHAC/PLGA composite membrane, while similar healing was only observed with pure PLGA implants after 8 weeks. This novel composite appears to be a very promising candidate for periodontal and bone defects therapy.