An osteogenic cell culture system to evaluate the cytocompatibility of Osteoset, a calcium sulfate bone void filler

Comparison of Outcomes Following TiRobot-Assisted Sacroiliac Screw Fixation with Bone Grafting and Traditional Screw Fixation without Bone Grafting for Unstable Osteoporotic Sacral Fracture: A Single-Center Retrospective Study of 33 Patients

BACKGROUND This retrospective study from a single center aimed to compare patient outcomes following TiRobot-assisted sacroiliac screw fixation and bone grafting with traditional screw fixation without bone grafting in 33 patients with unstable osteoporotic sacral fracture (UOSF). MATERIAL AND METHODS Patients with UOSF were included and divided into 2 groups: a TiRobot-assisted surgical group with 18 patients (robot-aided sacroiliac screw fixation and bone grafting) and a standard surgical group with 15 patients (free-hand screw fixation without bone grafting). T values of bone mineral density (BMD) £-2.5 standard deviation (SD) were diagnosed as osteoporosis. Screw positioning and fracture healing time were evaluated. Functional outcomes were investigated at the final follow-up. RESULTS There were no statistically significant differences in screw positioning; however, there were satisfactory positioning rates in 94.4% (17/18) of patients in the TiRobot-assisted surgical group and 73.3% (11/15) in the standard surgical group. The advantages with TiRobot on surgical time of screw placement, fluoroscopy frequency, and total drilling times were noted (P=0.000). The nonunion rates were 5.6% (1/18) in the TiRobot-assisted surgical group and 33.3% (5/15) in the standard group (P=0.039). Healing time in the union cases had a significant difference (P=0.031). Functional outcome scores in the TiRobot-assisted surgical group were superior to that in the standard group (P=0.014). CONCLUSIONS The findings showed that TiRobot-assisted sacroiliac screw fixation and bone grafting was a safe and effective surgical treatment option that had a reduced radiation dose and improved fracture healing, when compared with standard screw fixation without bone grafting.

Strontium Modified Calcium Sulfate Hemihydrate Scaffold Incorporating Ginsenoside Rg1/Gelatin Microspheres for Bone Regeneration

The aim of this study was to prepare a promising biomaterial for bone tissue repair and regeneration. The Strontium - calcium sulfate hemihydrate (Sr-α-CaS) scaffold incorporating gelatin microspheres (GMs) encapsulated with Ginsenoside Rg1 (Rg1) was designed. The scaffolds of Rg1/GMs/Sr-α-CaS showed sustained release of Rg1, good biocompatibility and ability of promoting osteogenic differentiation and angiogenesis in vitro. The scaffolds were implanted into animal model of cranial bone defect to characterize bone tissue repair and regeneration in vivo. From the images of Micro-CT, it was obvious that the most bone tissue was formed in Rg1/GMs/Sr-α-CaS group in 12 weeks. New bone structure, collagen and mineralization were analyzed with staining of HE, Masson and Safranin O-Fast green and showed good distribution. The expression of osteocalcin of Rg1/GMs/Sr-α-CaS indicated new bone formation in defect site. The results revealed that synergy of Rg1 and Sr showed the best effect of bone repair and regeneration, which provided a new candidate for bone defect repair in clinic.

Rapid Micelle-Mediated Size-Controlled Fabrication of Calcium Sulfate Nanorods Using Silver Nanoparticles

Calcium sulfate nanorods (CS-NRs) are valuable materials utilized in various applications, particularly in the medical field. In this work, the size-controlled synthesis of CS-NRs was carried out on the basis of the micelle-mediated phase separation phenomenon. A nonionic surfactant, Triton X-114, was employed for the thermoresponsive phase separation of a homogeneous solution to a surfactant-rich phase. Whereas each specific ion, Ca²⁺ and SO₄^2-, was difficult to individually extract when present at concentrations less than their equilibrium concentration (solubility product constant, K_sp), the synthesized CS microrods (CS-μRs) were extracted into the surfactant-rich phase (enrichment factor = ca. 50). The presence of nitric acid increased the size of the materials up to 6707 ± 3488 nm on the long side and 87 ± 37 nm on the short side. The addition of silver nanoparticles (Ag-NPs) to the reaction mixture led to the formation of much smaller products, i.e., uniform CS-NRs whose sizes were in the range of 89 ± 15 nm (long side) and 25 ± 4 nm (short side). The size of the extracted Ag-NPs and CS-NRs decreased with an increase in added Ag-NP concentration until their microscopic observation became difficult. The factors (such as additive concentration, pH, temperature) affecting size control were evaluated.

In Vitro Investigation of Cell Compatibility of Pure β-TCP Granules

In this study, osteoblastic cells were isolated from rat bone marrow and characterized. The cells were cultured on β-TCP granules and the osteoblast/ β-TCP constructs. For this purpose, bone marrow was harvested under sterile conditions. Cell aggregates were broken up by pipetting and a cell suspension was cultured in DMEM/F12. After three days, the cells that adhered to the surface of the flask were cultured in osteoblast medium. When the cells became confluent, they were passaged and cultured in 24-well polystyrene cell culture dishes. Characterization of the osteoblasts, cell proliferation and alkaline phosphatase activity were measured on days 1, 7, 14, 21 and 30. To investigate the cell compatibility of the β-TCP granules, osteoblastic cells were cultured on β-TCP granules and a polystyrene cell culture dish (control group). Cell proliferation and alkaline phosphatase (ALP) activity were measured on days 1, 7, 14, 21 and 30 in both groups. Cell growth significantly increased at each time point, but on day 30 a decrease was observed. The ALP activity also increased at each time point and also decreased on day 30. This study may be regarded as the first step leading to a therapy for various bone defects.

A critical review of cell culture strategies for modelling intracortical brain implant material reactions

The capacity to predict in vivo responses to medical devices in humans currently relies greatly on implantation in animal models. Researchers have been striving to develop in vitro techniques that can overcome the limitations associated with in vivo approaches. This review focuses on a critical analysis of the major in vitro strategies being utilized in laboratories around the world to improve understanding of the biological performance of intracortical, brain-implanted microdevices. Of particular interest to the current review are in vitro models for studying cell responses to penetrating intracortical devices and their materials, such as electrode arrays used for brain computer interface (BCI) and deep brain stimulation electrode probes implanted through the cortex. A background on the neural interface challenge is presented, followed by discussion of relevant in vitro culture strategies and their advantages and disadvantages. Future development of 2D culture models that exhibit developmental changes capable of mimicking normal, postnatal development will form the basis for more complex accurate predictive models in the future. Although not within the scope of this review, innovations in 3D scaffold technologies and microfluidic constructs will further improve the utility of in vitro approaches.

Composite chitosan and calcium sulfate scaffold for dual delivery of vancomycin and recombinant human bone morphogenetic protein-2

A biodegradable, composite bone graft, composed of chitosan microspheres embedded in calcium sulfate, was evaluated in vitro for point-of-care loading and delivery of antibiotics and growth factors to prevent infection and stimulate healing in large bone injuries. Microspheres were loaded with rhBMP-2 or vancomycin prior to mixing into calcium sulfate loaded with vancomycin. Composites were evaluated for set time, drug release kinetics, and bacteriostatic/bactericidal activity of released vancomycin, induction of ALP expression by released rhBMP-2, and interaction of drugs on cells. Results showed the composite set in under 36 min and released vancomycin levels that were bactericidal to S. aureus (>MIC 8-16 μg/mL) for 18 days. Composites exhibited a 1 day-delayed release, followed by a continuous release of rhBMP-2 over 6 weeks; ranging from 0.06 to 1.49 ng/mL, and showed a dose dependent release based on initial loading. Released rhBMP-2 levels were, however, too low to induce detectable levels of ALP in W20-17 cells, due to the affinity of rhBMP-2 for calcium-based materials. With stimulating amounts of rhBMP-2 (>50 ng/mL), the ALP response from W-20-17 cells was inhibited when exposed to high vancomycin levels (1,800-3,600 μg/mL). This dual-delivery system is an attractive alternative to single delivery or preloaded systems for bone regeneration since it can simultaneously fight infection and deliver a potent growth factor. Additionally, this composite can accommodate a wide range of therapeutics and thus be customizable for specific patient needs, however, the potential interactive effects of multiple agents must be investigated to ensure that functional activity is not altered.

EVALUATION OF CHITOSAN/CaSO4/PLATELET-RICH PLASMA MICROSPHERE COMPOSITES AS ALVEOLUS OSTEOGENESIS MATERIAL

Periodontal disease is the manifestation of serious bacteria infection that may extend to the gingival, periodontal ligaments, and alveolus bone. One commonly administrated treatment is the debridement therapy with the removal of infected area including the soft and hard lesion tissues. In some critical case, osteogenetic materials are being filled into the defective voids to improve the regeneration of slow-growing bony tissues. In attempt to improve bone regeneration, chitosan microsphere composites embedded with two osteogenesis beneficial ingredients, CaSO 4 and platelet-rich plasma (PRP), were fabricated by using a high voltage electrostatic field system. Three groups, chitosan/ CaSO 4 microspheres (Group A), chitosan/ CaSO 4 microspheres mixed with thrombin (Group B), and chitosan/ CaSO 4/PRP microspheres mixed with thrombin (Group C) were prepared. And, these chitosan-based composites were evaluated together with a control group in pig oral model for the bone regeneration study. The chitosan/ CaSO 4/PRP microsphere composites, exhibiting good sphericity, were in the range of 457.5 ± 59.3 μ m in diameter. Defects filled with Group B and Group C showed increases in new bone formation along with fibrous tissue regeneration as compared to that filled with Group A. The Masson's Trichrome stain observations suggested more abundant presence of fibrous collagen matrices around the defects after implanted with Group B over that of Group C microsphere composites. The preparation of chitosan/ CaSO 4-based microspheres was straight forward by using high voltage electrostatic field system. Furthermore, Chitosan/ CaSO 4-based microspheres with thrombin could be used successfully in regenerating new bone around the alveolus bone area.

Improvement on the performance of bone regeneration of calcium sulfate hemihydrate by adding mineralized collagen

Comparative investigations of bone regeneration performance for calcium sulfate hemihydrate (CaSO(4).(1/2)H(2)O; CSH) only and CSH with mineralized collagen are reported in this article. The mineralized collagen is the nanohydroxyapatite/collagen (nHAC). The investigations included biocompatibility in vitro and performance of bone repair in vivo. Quantitative and qualitative biocompatibility assays with bone stromal stem cells were performed. A critical box-shaped defect model in the mandible of the rabbit was used to evaluate the bone-remodeling ability of CSH and nHAC/CSH. Results in vitro indicated that the nHAC/CSH significantly improved bioactivity compared with that of CSH, especially in promoting cell adhesion. Further, a higher bone remodeling activity was observed around nHAC/CSH composite than the CSH, especially at the early stage of remodeling. This result means that nHAC/CSH could cause an earlier accelerator and better osseointegration for bone repair than CSH only.

Effects of chitosan-coated pressed calcium sulfate pellets combined with recombinant human bone morphogenetic protein 2 on bone formation in femoral condyle-contained bone defects

Calcium sulfate has a rapid degradation rate and little osteoinductive capability. Chitosan-coated pressed calcium sulfate pellets combined with recombinant human bone morphogenetic protein 2 (rhBMP-2) have been developed that exhibit decreased resorption speed and increased compressive strength and osteoinduction. A rabbit femoral condyle-contained bone defect model was used to study the restoration of the defects treated with chitosan-coated pressed calcium sulfate pellets combined with rhBMP-2, chitosan-coated pressed calcium sulfate pellets, and uncoated pressed calcium sulfate pellets. No pellets were implanted in the control group. After 3 and 13 weeks, the results indicated that chitosan-coated pressed calcium sulfate pellets exhibited relatively slower resorption that closely coincides with the growth rate of new bone and enhanced osteogenesis when combined with rhBMP-2.

Synthetic bone grafts, the role of the gypsum in bone substitution; molecular biological approach

A csontpótlást igénylő műtéti beavatkozások során a beültetésre kerülő csontpótló graft tulajdonságai meghatározzák az eljárás kimenetelét, rövid és hosszú távú sikerét. Munkánk első részében áttekintést adunk a modern csontpótló eljárások előnyeiről-hátrányairól, illetve részletesen foglalkozunk a gipsz szintetikus csontpótló graftként történő alkalmazásának lehetőségével. A kísérletes klinikai leírások biztonsággal és jó hosszú távú eredménnyel alkalmazható csonthiánykitöltő anyagként írják le a kalcium-szulfát-dihidrátot, azonban a gipsz csontsejtekre kifejtett hatása, a csontpótlás mechanizmusa nem ismert. Molekuláris biológiai módszerekkel vizsgáltuk a gipsz csontsejtekre gyakorolt hatását. Az egér-praeosteoblastok szaporodására ideális tenyésztőfelületnek bizonyult a gipsz, míg a klinikumban gyakran csonthiánykitöltő anyagként alkalmazott polimetil-metakrilát-csontcement gátolta a sejtek osztódását. A gipsz megváltoztatta a sejtek génkifejeződési profilját, a csontképződés irányába mutató gének expresszálódtak nagyobb mértékben a gipszes tenyészetekben, és ezekben a sejtkultúrákban emelkedett alkalikusfoszfatáz-aktivitást mértünk. Eredményeink molekuláris biológiai szempontból támasztották alá a gipsz szintetikus csontpótló graftként történő alkalmazásának létjogosultságát, a kalcium-szulfát-dihidrát új – a csontgyógyulást támogató – tulajdonságát is kimutatva.

Effect of gypsum on proliferation and differentiation of MC3T3-E1 mouse osteoblastic cells

Recently, calcium sulfate dihydrate has been demonstrated as safe biodegradable osteoconductive bone void filler. However, its exact mechanism of action on bone cells is yet unknown. In this study, the influence of gypsum on gene expression and proliferation of MC3T3-E1 mouse pre-osteoblastic cells was investigated. Cells were cultured on gypsum disc, slice, polymethylmethacrylate (PMMA), or plastic culture plate for 15 days. Cell viability, alkaline phosphatase (ALP) activity and expression profile of 15 genes involved in bone metabolism were measured in cultures. Cell proliferation on gypsum was increased by almost 2-fold, while an inhibitory effect of PMMA on proliferation rate of osteoblasts was noted. Cells cultured on gypsum disc surface exhibited an increased ALP activity and markedly different gene expression profile. Quantitative real-time PCR data indicated the expression of genes that might provide a basis for an osteoinductive potential. MC3T3-E1 cells expressed genes typical of bone fracture healing like type II collagen and fibronectin 1. These effects might be related to the calcium content of gypsum and mediated likely via SMAD3. Our results suggest that gypsum can support new bone formation by its calcium content and modulatory effect on gene expression profile of bone cells.

Characterization of chitosan films and effects on fibroblast cell attachment and proliferation

Chitosan has been researched for implant and wound healing applications. However, there are inconsistencies in reports on the tissue and fibroblast responses to chitosan materials. These inconsistencies may be due to variations in chitosan material characteristics. The aim of this study was to correlate fibroblast responses with known chitosan material characteristics. To achieve this aim, chitosan was characterized for degree of deacetylation (DDA), molecular weight (MW), residual protein and ash contents, and then solution cast into films and characterized for hydrophilicity by water contact angle. The films were seeded with normal human dermal fibroblasts and the number of attached cells was evaluated for after 30 min. Cell proliferation was evaluated over 5 days. This study found no relationship between DDA, contact angle, cell attachment, and or proliferation. General trends were observed for increasing proliferation with increasing residual ash content and decreasing residual protein. These data indicate that chitosan characteristics other than DDA may be important to their biological performance.

Biological effects of calcium sulfate as a bone graft substitute in ovine metaphyseal defects

Calcium sulfate has been used as a bone graft substitute in many fields, from dentistry to orthopedics. However, the results of many studies have yielded inconclusive results. In the present study, a sheep model was used with tibial and femoral metaphyseal defects to determine whether calcium sulfate was as effective as autograft and allograft in promoting new bone formation in a critical size defect. Medical-grade calcium sulfate pellets, autograft bone, allograft bone, or nothing was used to fill the metaphyseal defects. The sheep were allowed to heal for 12 weeks. Sagittal sections from the bones were analyzed with high-resolution contact radiographs, backscattered electron microscopy, and light microscopy. The volume fractions of bone within the defect perimeter were determined, and the histologic quality of the bone was observed. The volume fraction of new bone in the autograft, calcium sulfate, and allograft were not statistically different, but all were significantly different than the untreated control. The majority of the calcium sulfate had been resorbed at 12 weeks, and the histologic quality of the bone appeared similar to the autograft-treated bone. Calcium sulfate appears to be a useful biocompatible bone graft substitute that yields results similar to autograft bone in sheep metaphyseal defects.

Biocompatibility and integrin-mediated adhesion of human osteoblasts to poly(DL-lactide-co-glycolide) copolymers

The biocompatibility of polylactic acid (PLA) and polyglycolic acid (PGA) copolymers, employed in manufacturing bone-graft substitutes, is affected by their chemical composition, molecular weight and cell environment, and by the methods of polymerization and processing. Their in vitro bioactivity on human osteoblasts has been investigated very little. We first evaluated the behavior of primary human osteoblasts cultured in close contact with 75:25 and 50:50 PLA-PGA copolymers for 14 days adopting a cell culture system that allowed us to evaluate the influence of direct contact, and of factors released from polymers. The copolymers had no negative influence on cell morphology, cell viability and proliferation. Alkaline phosphatase (ALP) activity and osteocalcin production were also not affected. The initial adhesion of osteoblasts on implant surfaces requires the contribution of integrins, acting as a primary mechanism regulating cell-extracellular matrix (ECM) interactions. We observed that adhesion of osteoblasts to PLA-PGA copolymers, 2h after plating, was reduced by approximately 70% by antibodies capable to block integrin beta(1) and alpha(5)beta(1) complex and only by approximately 30% by an anti-integrin alpha(v) antibody. Therefore, beta(1) integrins may represent a predominant adhesion receptor subfamily utilized by osteoblasts to adhere to PLA-PGA copolymers. These materials do not show any negative influence on cell proliferation and differentiation.

Intracorporal bone grafting for vertebral compression fractures with intraosseous vacuum phenomenon

From April 1998 to January 2000 we treated 14 patients with vertebral osteoporotic compression fractures and intraosseous vacuum phenomenon with intracorporal bone grafting using a mixture of autogenous bone graft and calcium sulfate and posterior instrumentation. The mixture was packed into the fractured vertebral body through two tunnels created in the pedicles. Eleven patients were followed for a minimum of 24 months. All vertebral bodies healed. There were no perioperative complications. The average vertebral height restoration was 31%. On the visual analogue scale, there was an improvement of average 37 clinical scores.

Porous polymer scaffolds surface-modified with arginine-glycine-aspartic acid enhance bone cell attachment and differentiation in vitro

This study was designed to determine if the surface modification of porous poly(lactic acid) (PLA) scaffolds would enhance osteogenic precursor cell (OPC) attachment, growth, and differentiation. A covalently grafted amino group (-NH(2)), poly(L-lysine) (PLL), and the peptide arginine-glycine-aspartic acid (RGD) were selected for the evaluation. The hypothesis was that surface modification would have a positive impact on cell-substratum interactions. The experiment was performed by OPC cells being placed on PLA films and scaffolds modified with NH(2), PLL, or RGD in tissue culture media. OPC attachment to PLA films was assessed after 24 h of incubation. The growth and differentiation of the adherent OPCs on porous PLA scaffolds were assessed after 14 and 28 days for alkaline phosphatase (APase) activity and calcium levels, both of which increase as OPCs differentiate into mature bone cells. All assays were accomplished in triplicate, and data were tested with post hoc orthogonal contrasts (i.e., Fisher's least significant difference) at p < or = 0.05. The PLA film surface-modified with RGD showed better OPC cell attachment than the other films. The cells on the PLA scaffolds surface-modified with RGD also exhibited an increase in APase activity and calcium levels in comparison with those on other scaffolds. This difference was apparent at both time intervals and was especially evident in the tissue culture media containing an osteogenic supplement. The results of this study indicate that modifying the surface of PLA polymer scaffolds with RGD enhances bone cell attachment and differentiation and may improve their ability to regenerate bone tissue more efficiently in wound models.