Fabrication of Isoniazid/Rifampicin/Poly L-lactic Acid Donut-shaped Implants via Three Dimensional Printing Technique.

Objective To investigate the possibility of manufacturing dual-drug loaded isoniazid/rifampicin/poly L-lactic acid (PLLA) implant with donut-shaped structure via three-dimensional (3D) printing technique and study the drug release characteristic and biocompatibility of the implant in vitro.Methods PLLA was crushed into particles with diameters around 75-100 µm.Isoniazid and rifampicin bulk drugs were dissolved into the organic dissolvent respectively to be the binding liquid.The 3D printing machine fabricated the donut-shaped implant via binding the PLLA powder layer by layer.Dynamic socking method was used to study the in vitro release characteristics,and cell culture experiment was used to test the cytocompatibility of the implant.Results PLLA slow-release implants were made by using the PLLA powder as matrix and isoniazid/rifampicin organic solvent as binding liquid through 3D printing.The drugs in the implants distributed in nest under electron microscope.The concentrations of both drugs were still higher than the lowest effective bacteriostasis concentration after release for 32 days.Cytotoxicity and direct contact tests indicated that the implants had rare cytotoxicity and favorable biocompatibility. Conclusion The donut-shaped implants can be successfully fabricated using the 3D printing method,which offers a new method for the manufacturing of topical slow-release anti-tuberculosis drugs.

In vivo testing of canine prosthetic femoral components with HA-Ti ladder-type coating on vacuum plasma-sprayed Ti substrate.

The purpose of the present study was to observe the structure and functional change of the bone-coating-prosthesis interface in vivo and to evaluate the histocompatibility of self-made prosthetic femoral components in the body and the degree of their bonding with the surrounding bone tissues as well as their stability. Six mature beagle dogs underwent bilateral hip replacement with prosthetic femur components. Three groups were established in terms of different coating of prothesis (four joints in each group): atmosphere (A) plasma-sprayed pure titanium (Ti) prosthetic joint with hydroxyapatite (HA) coating (HA+Ti+A group); vacuum (V) plasma-sprayed pure Ti prosthetic joint with HA coating (HA+Ti+V group); vacuum plasma-sprayed pure Ti prosthetic joint with Ti-HA stepped coating (Ti+HAG+Ti+V group). The hip joints were functionally evaluated, and subjected to X-ray examination, biomechanics inspection, and histological examination. As a result, X-ray imaging revealed all prosthetic joints were in a good location and no dislocation of joint was found. Shear strength of interface was significantly higher in Ti+HAG+Ti+V group than in HA+Ti+V group (P<0.05) and HA+Ti+A group (P<0.05) at 28th week. Histological examination showed the amount of newborn bone in Ti+HAG+Ti+V group was more than in HA+Ti+V group and HA+Ti+A group after 28 weeks. It was suggested that vacuum plasma-sprayed pure Ti prosthetic joint with TI-HA stepped coating could improve the bonding capacity of bone-prosthesis, enhance the stability of prosthesis, and increase the fixion of prosthetic femoral components because of better bone growth. This new type of biological material in prosthetic femoral components holds promises for application in clinical practice.

[Synthetic RGD-containing peptide K16GRGDSPC affected the adhesion, proliferation and osteogenic differentiation of rabbit bone marrow stromal cells on PLGA-[ASP-PEG] scaffold materials].

OBJECTIVE: To explore the effects of synthetic RGD-containing peptide K16GRGDSPC covalent bonding with PLGA-[ASP-PEG] scaffold materials on the adhesion, proliferation and osteogenic differentiation of rabbit bone marrow stromal cells (BMSCs). METHODS: The peptide was synthesized by solid-phase synthesis method and characterized by mass spectrometry and high pressure liquid chromatography. PLGA-[ASP-PEG] scaffold materials were modified with the peptide by cross linker Sulfo-LC-SPDP and detected by XPS. The BMSCs obtained from rabbit were cultured on PLGA-[ASP-PEG] modified with the peptide and those cultured on unmodified PLGA-[ASP-PEG] were also observed as control group. The adhesion and proliferation behaviors of the cells were analyzed by conventional precipitation method, micropipette aspiration technique, MTT assay and Coomassie Brilliant Blue dyes. The osteogenic differentiation of the cells was showed by the activity of alkaline phosphatase (ALP) assayed by ALP Assay Kit and the mRNA levels of ALP, osteocalcin (OCN), osteopontin (OPN) and collagen I assessed by real-time PCR (RT-PCR). Immunofluorescence stain was also used to detect the expression of core binding factor a1 (Cfba1) which was an osteogenic maker as well. RESULTS: The peptide was successfully manufactured and linked to the surface of the PLGA-[ASP-PEG] by the cross-linker. The abilities of adhesion and proliferation and the expressions of osteogenic makers of the cells were significantly higher than those of control group (P < 0.05). CONCLUSION: RGD-containing peptide K16GRGDSPC could promote the adhesion, proliferation and osteogenic differentiation of BMSCs on the biomimetic bone-matrix materials.

Bone induction by biomimetic PLGA-(PEG-ASP)n copolymer loaded with a novel synthetic BMP-2-related peptide in vitro and in vivo.

BMP-2 is one of the most important growth factors of bone regeneration. Polylactide-co-glycolic acid (PLGA), which is used as a biodegradable scaffold for delivering therapeutic agents, has been intensively investigated. In previous studies, we synthesized a novel BMP-2-related peptide (designated P24) and found that it could enhance the osteoblastic differentiation of bone marrow stromal cells (BMSCs). The objective of this study was to construct a biomimetic composite by incorporating P24 into a modified PLGA-(PEG-ASP)n copolymer to promote bone formation. In vitro, our results demonstrated that PLGA-(PEG-ASP)n scaffolds were shown to be an efficient system for sustained release of P24. Significantly more BMSCs attached to the P24/PLGA-(PEG-ASP)n and PLGA-(PEG-ASP)n membranes than to PLGA, and the cells in the two groups subsequently proliferated more vigorously than those in the PLGA group. The expression of osteogenic markers in P24/PLGA-(PEG-ASP)n group was stronger than that in the PLGA-(PEG-ASP)n and PLGA groups. Radiographic and histological examination, Western blotting and RT-PCR showed that P24/PLGA-(PEG-ASP)n scaffold could induce more effective ectopic bone formation in vivo, as compared with PLGA-(PEG-ASP)n or gelatin sponge alone. It is concluded that the PLGA-(PEG-ASP)n copolymer is a good P24 carrier and can serve as a good scaffold for controlled release of P24. This novel P24/PLGA-(PEG-ASP)n composite promises to be an excellent biomaterial for inducing bone regeneration.

[Adhesion, proliferation and osteodifferentiation of bone mesenchymal stem cells on PLGA-[ASP-PEG] tri-bolck polymer scaffolds].

OBJECTIVE: To explore the adhesion,proliferation and osteodifferentiation of bone mesenchymal stem cells (BMSCs)on the prepared lactic acid/glycolic acid/asparagic acid-co-polyethylene glycol(PLGA-[ASP-PEG])tri-block polymer scaffolds. METHODS: Modified PLGA with polyethylene glycol (PEG) and asparagic acid(ASP)that has many liga nds,and then the synthesis PLGA-[ASP-PEG] tri-block polymer material was prepared. BMSCs were cultured in PLGA-[ASP-PEG] polymer material and poly lactic acid-co-glycolic acid(PLGA)were used as control group. Precipitation method, MUT assay and total cellular protein detection were used to test the adhersion and proliferation of BMSCs. After the third generation of BMSCs was cultured on PLGA-[ASP-PEG] tri-block polymer scaffolds for 14 day and 28 day with osteogenic supplements,the osteodifferentiation of MSCs were observed through alkaline phosphatase(ALP) staining and calcium tubercle staining. RESULTS: BMSCs grew adherent to the surface of PLGA-[ASP-PEG] polymer scaffolds and the number of BMSCs was much higher than that of PLGA. The precipitation method suggested that adhesion and proliferation of BMSCs on the surface of PLGA-[ASP-PEG] was much higher than the control group (P < 0.05). MTU assay showed that after BMSCs were cultured for 20 days,the absorbance A of PLGA-[ASP-PEG] polymer scaffolds and PLGA were 1.336 and 0.780 respectively. Total cellular protein could image the adhersion and proliferation of BMSCs indirectly. After BMSCs were cultured for 12 days,the total cellular protein of PLGA-[ASP-PEG] and PLGA were 66.44 microg/pore and 41.23 microg/pore respectively. PLGA-[ASP-PEG] polymer scaffolds had well biocompatibility and cell adhersion. The positive results with ALP staining and calcium tubercle staining in both groups indicated tri-block polymer scaffold and its degradations had no effect on osteodifferentiation. CONCLUSION: PLGA-[ASP-PEG]could improve the adhesion and proliferation of seed cells on bone-matrixmaterial, maintain the morphous of seed cells and had no obvious effect on cell osteodifferentiation.