Cell Osteogenic Activity Research Articles

3D-printed porous zinc scaffold combined with bioactive serum exosomes promotes bone defect repair in rabbit radius.

Currently, the repair of large bone defects still faces numerous challenges, with the most crucial being the lack of large bone grafts with good osteogenic properties. In this study, a novel bone repair implant (degradable porous zinc scaffold/BF Exo composite implant) was developed by utilizing laser melting rapid prototyping 3D printing technology to fabricate a porous zinc scaffold, combining it under vacuum conditions with highly bioactive serum exosomes (BF EXO) and Poloxamer 407 thermosensitive hydrogel. The electron microscope revealed the presence of tea saucer-shaped exosomes with a double-layered membrane structure, ranging in diameter from 30-150 nm, with an average size of 86.3 nm and a concentration of 3.28E+09 particles/mL. In vitro experiments demonstrated that the zinc scaffold displayed no significant cytotoxicity, and loading exosomes enhanced the zinc scaffold's ability to promote osteogenic cell activity while inhibiting osteoclast activity. In vivo experiments on rabbits indicated that the hepatic and renal toxicity of the zinc scaffold decreased over time, and the loading of exosomes alleviated the hepatic and renal toxic effects of the zinc scaffold. Throughout various stages of repairing radial bone defects in rabbits, loading exosomes reinforced the zinc scaffold's capacity to enhance osteogenic cell activity, suppress osteoclast activity, and promote angiogenesis. This effect may be attributed to BF Exo's regulation of p38/STAT1 signaling. This study signifies that the combined treatment of degradable porous zinc scaffolds and BF Exo is an effective and biocompatible strategy for bone defect repair therapy.

Novel barium-doped-baghdadite incorporated PHBV-PCL composite fibrous scaffolds for bone tissue engineering

Bioceramic/polymer composites have dragged a lot of attention for treating hard tissue damage in recent years. In this study, we synthesized barium-doped baghdadite (Ba-BAG), as a novel bioceramic, and later developed fibrous composite poly (hydroxybutyrate) co (hydroxyvalerate)- polycaprolactone (PHBV-PCL) scaffolds containing different amounts of baghdadite (BAG) and Ba-BAG, intended to be used in bone regeneration. Our results demonstrated that BAG and Ba-doped BAG powders were synthesized successfully using the sol-gel method and their microstructural, physicochemical, and cytotoxical properties results were evaluated. In the following, PHBV/PCL composite scaffolds containing different amounts of BAG and Ba-BAG (1, 3, and 5 wt%) were produced by the wet electrospinning method. The porosity of scaffolds decreased from 78% to 72% in Ba-BAG-incorporated PHBV/PCL scaffolds. The compressive strength of the scaffolds was between 4.69 and 9.28 kPa, which was increased to their maximum values in the scaffolds with Ba-BAG. The presence of BAG and Ba-BAG in the polymer scaffolds resulted in increasing bioactivity, and it was introduced as a suitable way to control the degradation rate of scaffolds. The presence of the BAG component was a major reason for higher cell proliferation in reinforced PHBV/PCL polymeric scaffolds, while Ba existence played its influential role in the higher osteogenic activity of cells on Ba-BAG incorporated PHBV/PCL scaffolds. Thus, the incorporation of Ba-BAG bioceramic materials into the structure of polymeric PHBV/PCL scaffolds promoted their various properties, and allow these scaffolds to be used as promising candidates in bone tissue engineering applications.

Diatom silica frustules-doped fibers for controlled release of melatonin for bone regeneration

Sustained release of a bioactive agent from a tissue engineering scaffold is one of the most common strategies to improve regenerative potential of the construct. However, depending on the chemistry of the agent, achieving high enough loading and controlled release can be challenging depending on the scaffold materials. These shortcomings can be solved by novel scaffold design fabricated by appropriate techniques and materials for the target tissue. In this study, an electrospun scaffold was designed to improve osteogenic activity of cells and diatom silica frustules were used to sustain loading and controlled release of a hydrophilic molecule, melatonin. Fibrous scaffolds were produced via wet electrospinning of the polymer blend solution poly(hydroxybutyrate-co-hydroxyvalerate (PHBV)/poly(ε-caprolactone) (PCL) which contains melatonin loaded diatom frustules. In the 3D fiber matrix diatom frustules were covered with a polymer coat which successfully lowered melatonin release more than half through 7 days achieving a controlled release. Melatonin had a concentration dependent effect on ALP activity of cells, while scaffolds bearing melatonin loaded frustules have significantly improved ALP activity of Saos-2 cells. Developed scaffold system has successfully induced osteogenic activity by controlled melatonin delivery and silica nature of diatom frustules which hold potential use for bone tissue engineering.

METTL14 upregulates TCF1 through m6A mRNA methylation to stimulate osteogenic activity in osteoporosis.

Alteration of N6-methyladenosine (m6A) is closely linked to spanning biological processes including osteoporosis (OP) development. This research focuses on the function of methyltransferase like 14 (METTL14) in bone turnover and its interaction with T cell factor 1 (TCF1). A mouse model of OP was established by ovariectomy (OVX). The bone mass parameters were evaluated by micro-CT analysis. Mouse MC3T3-E1 cells and mouse bone marrow macrophages (BMMs) were induced for osteogenic or osteoclastic differentiation, respectively, for in vitro experiments. The osteogenesis or osteoclasis activity was analyzed by measuring the biomarkers such as OPG, ALP, NFATC1, CTSK, RANKL, and TRAP. RT-qPCR and IHC assays identified reduced METTL14 expression in bone tissues of osteoporotic patients and ovariectomized mice. Artificial METTL14 overexpression increased bone mass of mice and promoted osteogenesis whereas suppressed osteoclasis both in vivo and in vitro. METTL14 promoted TCF1 expression through m6A mRNA methylation, and TCF1 increased the osteogenic activity by elevating the protein level of RUNX2, a key molecule linked to bone formation. In rescue experiments, TCF1 restored the RUNX2 level and osteogenic activity of cells suppressed by METTL14 silencing. In summary, this research demonstrates that METTL14 plays a protective role against OP by promoting the TCF1/RUNX2 axis.

Effects of the doping concentration of boron on physicochemical, mechanical, and biological properties of hydroxyapatite

Ion doping is an approach to modify properties of materials, like hydroxyapatite (HA), that contributes to designing biomaterials with desired characteristics applicable in bone defect treatments. Recently, boron (B) has been noticed in biomaterial fields due to its beneficial effects on formation, growth, and quality of bone. In this study, B-doped HA nanoparticles with different molar concentrations of B (0.05, 0.1, 0.25, and 0.5) were synthesized through microwave-assisted wet precipitation. The effects of B content on various properties of HA were evaluated. The results demonstrated that the size of HA particles reduced from 106 nm to 89-85 nm in B doped materials. Meanwhile, the crystallinity degree of B doped HA (BHA) samples was between 89.90% and 93.77%, compared to 95.19% of HA. Diametral tensile strength of samples was measured in the ranges of 2.51 and 3.61 with no significant difference among groups. The micro-hardness of HA was 0.88 GPa, whilst doped ones had hardness values of 0.5 GPa–0.68 GPa. Biodegradability of samples increased from less than 1% to approximately 4% after 28 days, while B-doping did not make any change in the degradation rate. Doping dosages were appropriate in terms of bioactivity and cell viability, and B doping caused higher bioactivity and cell proliferation. All changed properties were dose-dependent and more effective in doped groups with a higher amount of B. Despite proliferative effect, 260 μg/l and 770 μg/l of B release in two groups with the highest dopant concentrations did not positively influence the osteogenic activity of cells. Our results demonstrated that doping concentrations that resulted in B release ≤260 μg/l seem more appropriate dosage, especially for bone tissue engineering and substitute applications due to promoted bioactivity and proliferation, as well as no obstructive effects on mechanical properties and osteogenic activities of HA.

Rational design and fabrication of monophasic bioceramic microspheres with enhanced mechanical and biological performances in reconstruction of segmental bone defect.

Over the past decades, there has been extensive study on the design of porous bioceramic scaffolds with controlled bioactivity and biodegradation in bone tissue repair. A variety of suggestive models and concepts have been proposed with regard to the role of microstructure and composition of biomaterials which affect new bone tissue growth. However, it is a challenge to fabricate functional scaffolds with the desired physiological properties and osteogenic potentials that is comparable to the bone's natural healing time scale. We demonstrate a one-step versatile fabrication of a single-phase and homogenously mixed bioactive load-bearing scaffolds (Sr-CS, CaSiO3/Ca2SiO4, and CaP) with superior biological properties in a critical size bone defect (Ø ~ 6.0 × 8.0mm). In vivo study revealed the CaSiO3/Ca2SiO4 scaffold had the best amount of new bone growth and osteogenic repair. The Sr-CS exhibited an adequate pore network for rapid inorganic exchange and moderate mechanical stability; however, the CaSiO3/Ca2SiO4 saw over-fast resorption and mass loss compared to the Sr-CS and CaP. On the other hand, the CaP scaffold saw mechanically outstanding elastroplastine and stability but had limited biodegradation of its constructs which retarded new cancellous bone growth. The CaSiO3/Ca2SiO4 group saw superior acceleration and formation of mineralized new bone tissues in the defect. Moreover, the CaSiO3/Ca2SiO4 showed appreciable decay of the biomaterials beneficial for osteogenic cell activity. The dramatic stimulation of bone repair and angiogenesis with the CaSiO3/Ca2SiO4 suggests a promising application of this novel bioactive scaffold in the repair of skeletal defects. Systemic representation of the fabricated microspheres with in vivo and in vitro study analysis.

Bioinspired Silk Fibroin-Based Composite Grafts as Bone Tunnel Fillers for Anterior Cruciate Ligament Reconstruction.

Anterior cruciate ligament (ACL) replacement is still a big challenge in orthopedics due to the need to develop bioinspired implants that can mimic the complexity of bone-ligament interface. In this study, we propose biomimetic composite tubular grafts (CTGs) made of horseradish peroxidase (HRP)-cross-linked silk fibroin (SF) hydrogels containing ZnSr-doped β-tricalcium phosphate (ZnSr-β-TCP) particles, as promising bone tunnel fillers to be used in ACL grafts (ACLGs) implantation. For comparative purposes, plain HRP-cross-linked SF hydrogels (PTGs) were fabricated. Sonication and freeze-drying methodologies capable of inducing crystalline β-sheet conformation were carried out to produce both the CTGs and PTGs. A homogeneous microstructure was achieved from microporous to nanoporous scales. The mechanical properties were dependent on the inorganic powder’s incorporation, with a superior tensile modulus observed on the CTGs (12.05 ± 1.03 MPa) as compared to the PTGs (5.30 ± 0.93 MPa). The CTGs presented adequate swelling properties to fill the space in the bone structure after bone tunnel enlargement and provide a stable degradation profile under low concentration of protease XIV. The in vitro studies revealed that SaOs-2 cells adhered, proliferated and remained viable when cultured into the CTGs. In addition, the bioactive CTGs supported the osteogenic activity of cells in terms of alkaline phosphatase (ALP) production, activity, and relative gene expression of osteogenic-related markers. Therefore, this study is the first evidence that the developed CTGs hold adequate structural, chemical, and biological properties to be used as bone tunnel fillers capable of connecting to the ACL tissue while stimulating bone tissue regeneration for a faster osteointegration.

K+/Sr2+/Na+ triple-doped hydroxyapatites/GelMA composite hydrogel scaffold for the repair of bone defects

One of the most important characteristics of desirable bone repair materials is to mimic the functions of human bones such as the storage/release of ions to maintain ionic homeostasis. In attempt to mimic natural Hydroxyapatite (HAP: Ca10(PO4)6(OH)2) in bones, HAP nanoparticles containing three abundant ions in human skeletal tissue (K+, Sr2+ and Na+) were designed and synthesized. The structures, morphologies, functional groups and cellular viability of the developed systems were examined to determine the precipitation conditions for generating pure phases of K+/Sr2+/Na+ triple-substituted nanoparticles. Notably, K+/Sr2+/Na+ triple-doped HAP nanoparticles were evaluated in vitro using osteoblasts cell line MC3T3-E1 to confirm the improved proliferation compared to bone cells grown with HAP without ion substitution. This study provides a bone material platform based on GelMA hydrogel that can deliver therapeutic ions in a biomimetic manner, and demonstrates the impact of ions on the osteogenic activity of cells.

<i>In vitro</i> induction of regenerative and osteogenic activity of PDLSC cells

The restoration of damaged tissues in periodontal diseases is not only a medical problem, but also a social one. Periodontal diseases often entail the loss of a large number of teeth (more than with any other disease of the dentition), as a result, a violation of the act of chewing and speech, a negative effect on the general condition of the body and, as a result, a decrease in the quality of human life. Purpose of the study: to study the regenerative activity of a lyophilized extract of a chicken embryo of various concentrations in the composition of hyaluronic acid in relation to the culture of PDLSC cells in an in vitro experiment. Comparison groups: A solution of 1% unmodified hyaluronic acid containing lyophilized chicken embryo extract in three concentrations: 300 μg/ml, 150 μg/ml, 75 μg/ml. As a control, 1% solution of unmodified hyaluronic acid. Hyaluronic acid is a natural substance that is an important component of the extracellular matrix as a mineralized and non-mineralized tissue. Its use attracts the attention of specialists as an object capable of acquiring new properties with its various modifications. In our laboratory studies, stem cells from a culture of human periodontal disease were used. Periodontitis stem cells (PDLSC periodontal ligament) were discovered in 2004. Cell adhesion and tissue penetration were investigated by impedimetry. Analysis to assess cell viability was carried out using a solution containing a water-soluble tetrazolium salt. Differentiation of osteogenic direction without induction was measured three weeks after dilution of stem cells in traditional culture medium. Staining was carried out according to the Koss method. To assess mineralization, cells were stained with alizarin red, followed by assessment of calcium deposition in them. It was found that the resulting PDLSC cell population during the experiment was heterogeneous and showed healthy fibroblast morphology in all three study groups. Lyophilized extract of chicken embryo as part of a preparation based on hyaluronic acid does not significantly affect the survival and proliferation of PDLSC cells, however, at high concentrations (150 μg/ml and 300 μg/ml) it induces osteogenic activity of cells, increases mineralization without causing calcium deposition, which indicates regenerative activity. Osteogenic transdifferentiation is an attractive way to create cells of osteogenic cellular origin. The results of our study show that they can be used to model bone diseases.

Digital light processing strength-strong ultra-thin bioceramic scaffolds for challengeable orbital bone regeneration and repair in Situ

The orbital fracture regeneration and reconstruction is still a catastrophic challenge due to the extremely thin anatomical structure and different defect shapes in various clinical conditions. The conventional biomaterials and preparation technique are often inefficient in satisfying porous scaffold architecture designs with respect to their required structural stability and biological performances. Here we developed the ultrathin scaffolds with high- precision pore structure and appreciable osteogenic activity for orbital bone repair via digital light processing (DLP) stereolithography. The dilute magnesium-substituting wollastonite (CSi-Mg) bioceramic scaffolds of ~1.5 mm in thickness and over 60% in porosity were investigated systematically, and compared with another calcium-magnesium silicate (i.e. akermanite) and the pure wollastonite porous counterparts. The results showed that the flexural strengths (~6−22 MPa) and in vitro biodegradation of such bioceramic scaffolds could be tuned during their chemical composition (i.e. Mg content) design stage, and the CSi-Mg scaffolds were also beneficial for osteogenic cell activity in vitro. In particular, the CSi-Mg scaffolds could readily enhance the new bone ingrowth at 4 weeks of implantation in a critical-sized rabbit orbital bone defect model, and such strength-strong scaffolds exhibited outstanding orbital defect repair efficacy after 12 weeks of implantation, in comparison with the structural instability of other scaffolds. Basically, it is demonstrated that the dilute magnesium doping in wollastonite bioceramic can be favorable for developing the mechanically reliable scaffolds with high porosity and bioactivity but quite thin wall morphology, and meanwhile the DLP-assisted additive manufacturing help us to optimize such porous bioceramic design with respect to their required structural stability for orbital bone reconstruction.

Biofabrication and Characterization of Alginate Dialdehyde-Gelatin Microcapsules Incorporating Bioactive Glass for Cell Delivery Application.

The effect of the incorporation of 45S5 bioactive glass (BG) microparticles (mean particle size ≈2µm) on the fabrication and physicochemical properties of alginate dialdehyde-gelatin hydrogel capsules is investigated. The addition of BG particles decreases the hydrogel gelation time by ≈79% and 91% for the samples containing 0.1% w/v and 0.5% w/v BG, respectively. Moreover, it results in increasing average diameter of hydrogel capsules produced via a pressure-driven extrusion technique from about 1000µm for the samples without BG to about 1700 and 1900µm for the samples containing BG at concentrations of 0.1% w/v and 0.5% w/v, respectively. The presence of BG particles in the capsules decreases the degradation rate and improves the bioactivity of the materials. The viability of MG-63 cells encapsulated in all samples increases during the first 7d of cultivation and maintains the same level during 21d of cultivation. The early cell viability in samples containing BG is lower than that in samples without BG. The results show that 45S5 BG can positively regulate the osteogenic activity of cells incorporated in hydrogel capsules. The fabricated composite capsules exhibit promising potential for cell delivery in bone regeneration applications.

Effects of the Whey Protein Hydrolysates of Various Protein Enzymes on the Proliferation and Differentiation of 3T3-E1 Osteoblasts.

In this study, we used various proteinases to investigate the effect of whey protein hydrolysates on proliferation and differentiation of MC3T3-E1 osteoblasts. To confirm hydrolysis of the whey protein hydrolysates, the yield and α-amino acid content were determined. Since osteogenic cell activity is an important factor in osteogenesis, we evaluated the proliferation of osteogenic cells by measuring 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and alkaline phosphatase (ALP) activity. To analyze bone matrix formation, we identified calcium deposition by staining with Alizaline red-S. The free amino acid content was significantly higher in the whey protein hydrolysates prepared using Protamex, Flavourzyme, and Alcalase than in the control. When cells were treated with 500 μg/mL of whey protein hydrolysates prepared using Protamex and Alcalase, cell proliferation increased by 120% and 130%, respectively, compared with the control group. In addition, ALP activity was significantly higher following treatment with 500 μg/mL of whey protein hydrolysates prepared using Protamex and Alcalase (142.61% and 135.06%, respectively; P<0.05). Furthermore, when treated with 125 μg/mL of the same hydrolysates, the rate of calcium deposition increased significantly to 157.56% compared with the control group (P<0.05). Therefore, our results suggest that whey protein hydrolysates prepared using Protamex and Alcalase may have more beneficial effects on osteoblast proliferation and bone health than those prepared using other proteolytic enzymes.

Interrogating the Osteogenic Potential of Implant Surfaces In Vitro: A Review of Current Assays.

The success of implantable devices relies heavily on their interaction with the host cells facilitating the osseointegration process. However, with so many new surface modifications, with subtly varying design parameters, in vitro assays can, with proper interpretation, provide valuable information for understanding cellular behavior. This review brings together pertinent in vitro experimental protocols available to researchers and discusses them in relationship to the development of the osteoblast phenotype during bone repair. Consideration is also paid to the influence of endothelial and macrophage cells that can substantially change osteogenic cell activity and thus can provide added value for predicting the osseointegration potential in vivo. Due to the diverse and heterogeneous nature of cell types available for culture use, this review concludes that there is no "gold standard" series of assays. Rather, we present guidance in the experimental design of in vitro assays to better identify those surfaces with promising osteogenic potential. Impact statement Titanium implants are already widely used in orthopedics and dentistry, yet, intensive research continues with the aim of modifying and functionalizing implant surfaces to invoke a stronger bone response and to meet current clinical challenges around improving longevity, decreasing morbidity, widening access, and clinical application. A very large number of surface modifications have been studied and the potential for new designs appears to be limitless as new technology grows. This review provides guidance for in vitro assays available to test these technologies, providing a cost-effective means for acquiring robust and physiologically relevant data, before in vivo examination.

Electro-conductive carbon nanofibers as the promising interfacial biomaterials for bone tissue engineering

Electro-conductive nanomaterials are promising interfacial platforms to manipulate and electrically stimulate electroresponsive cells for tissue engineering proposes. The present study aimed to fabricate electro-conductive electrospun carbon nanofibers (CNFs) to be used as the substrate for bone cells electrical stimulation. The CNFs were derived from electrospun polyacrylonitrile (PAN) nanofibers by a two steps heat treatment, stabilization and carbonization. The seeded CNFs with Mg-63 cells (SCNFs) were exposed to DC electrical fields with the current intensities of 10, 50, 100, and 200 μA. COMSOL Multiphysics software was used to simulate the applied DC electric field applied in the fabricated electrical stimulation chamber in the presence of the SCNFs. The simulation study confirmed the efficacy of the fabricated electrical stimulation set-up. The growth of the seeded cells was significantly increased in the presence of the applied DC electric field and resulted in the highest proliferation level, 116.43 ± 4.76%, at 100 μA. The alkaline phosphatase (ALP) activity assay revealed increased osteogenic activity of cells, necessary for the enhanced bone healing process, as a result of the applied field. The present study indicates the efficiency of conductive CNFs for bone growth and that the electrical sensitivity of the substrate fabricated here might complement the piezoelectric characteristics of bone to further promote and facilitate bone growth and healing.

Synergistic interplay between the two major bone minerals, hydroxyapatite and whitlockite nanoparticles, for osteogenic differentiation of mesenchymal stem cells

The inorganic part of human bone is mainly composed of hydroxyapatite (HAP: Ca10(PO4)6(OH)2) and whitlockite (WH: Ca18Mg2(HPO4)2(PO4)12) minerals, where the WH phase occupies up to 20–35% of total weight. These two bone minerals have different crystal structures and physicochemical properties, implying their distinguished role in bone physiology. However, until now, the biological significance of the presence of a certain ratio between HAP and WH in bone is unclear. To address this fundamental question, bone mimetic scaffolds are designed to encapsulate human mesenchymal stem cells (MSCs) for assessing their osteogenic activity depending on different ratios of HAP and WH. Interestingly, cellular growth and osteogenic differentiation are significantly promoted when MSCs are grown with a 3–1 ratio of HAP and WH nanoparticles, which is similar to bone. One of the reasons for this synergism between HAP and WH in hydrogel scaffolds is that, while WH nanoparticles can enhance osteogenic differentiation of MSCs compared to HAP, WH counterintuitively decreases the mechanical stiffness of nanocomposite hydrogels and hinders the osteogenic activity of cells. Taken together, these findings identify the optimal ratio between two major minerals in bone mimetic scaffolds to maximize the osteogenic differentiation of MSCs. Statement of significanceHuman bone minerals are composed of HAP and WH inorganic nanoparticles which have different material properties. However, the reason for the coexistence of HAP and WH in human bone is not fully identified, and HAP and WH composite biomaterial has not been utilized in the clinic. In this study, we have developed bone mimetic HAP and WH nanocomposite hydrogel scaffolds with various ratios. Importantly, we found out that HAP can promote the mechanical stiffness of the composite hydrogel scaffolds while WH can enhance the osteogenic activity of stem cells, which together induced synergism to maximize osteogenic differentiation of stem cells when mixed into 3–1 ratio that is similar to human bone.

Synthesis, physico-chemical and biological characterization of strontium and cobalt substituted bioactive glasses for bone tissue engineering

Due to their vast potential for repair and regeneration, different types of bioactive glasses (BGs) have been widely studied for bone tissue engineering. In this study, different groups of melt-derived bioactive glasses containing strontium (Sr2+) and cobalt (Co2+) ions have been designed to investigate their potential effect on increasing cell osteogenic activity. After full characterization of the synthesized bioactive glasses, they were evaluated for apatite forming ability in simulated body fluid (SBF) after different time intervals. The glasses have been examined for cell attachment and cell cytotoxicity plus their influence on osteogenic activity of the cells was analyzed by alkaline phosphatase assay (ALP) and alizarin red staining. The results show that the samples are in glassy state before immersion in SBF and an apatite-like layer has formed on the surface of SBF-immersed samples after 3, 7 and 14days. In vitro experiments demonstrated that the incorporation of Sr2+ and Co2+ in the glass composition significantly promote osteogenic activity of human osteosarcoma cells without any cytotoxicity effect.

Sintering of calcium phosphates with a femtosecond pulsed laser for hard tissue engineering

Direct laser sintering on hard tissues is likely to open new pathways for personalised medicine. To minimise irradiation damage of the surrounding soft tissues, lasers operating at wavelengths that are ‘safe’ for the tissues and biomaterials with improved optical properties are required. In this work laser sintering is demonstrated with the use of an ultrafast, femtosecond (100fs) pulsed laser operating at a wavelength of 1045nm and two existing calcium phosphate minerals (brushite and hydroxyapatite) which have been improved after doping with iron (10mol%). Femtosecond laser irradiation caused transformation of the Fe3+-doped brushite and Fe3+-doped HAp samples into β-calcium pyrophosphate and calcium-iron-phosphate, respectively, with simultaneous evidence for microstructural sintering and densification. After estimating the temperature profile at the surface of the samples we suggest that soft tissues over 500μm from the irradiated zone would be safe from thermal damage. This novel laser processing provides a means to control the phase constitution and the morphology of the finished surfaces. The porous structure of β-pyrophosphate might be suitable for applications in bone regeneration by supporting osteogenic cell activity while, the densified Fe3+-rich calcium-iron-phosphate may be promising for applications like dental enamel restoration.

Preparation of mussel-inspired 3D polycaprolactone scaffolds and grafted with rhBMP-2 for bone tissue engineering

Event Abstract Back to Event Preparation of mussel-inspired 3D polycaprolactone scaffolds and grafted with rhBMP-2 for bone tissue engineering Sang Jin Lee1, 2, Wan-Kyu Ko1, Na Re Ko1, Min Heo1, Su A Park2 and Il Keun Kwon1 1 Kyung Hee University, Department of Maxillofacial Biomedical Engineering and Institute of Oral Biology, Korea 2 Korea Institute of Machinery and Materials, Department of Nature-Inspired Nanoconvergence Systems, Korea Introduction: In the tissue engineering area, the bio-compatible scaffold for bone tissue regeneration should provide not only surface of excellent hydrophilicity for cell attachment onto substrate, but also binding an efficiency of bio-active molecule such as growth factor to promote a differentiation of cells. In this work, thus, we prepared a recombinant human bone morphogenic protein-2 (rhBMP2) grafting on three-dimensional (3D) polycaprolactone scaffold (PCLS)[1],[2] using polydopamine (DOPA) chemistry. Material and Method: The DOPA coated PCL scaffold was characterized by contact angle, water uptake, and x-ray photoelectron spectroscopy (XPS) test to certify whether coated DOPA or not. In order to systematize the loading efficiency of rhBMP2, we examined the releasing test for 21 days. In vitro cell study, pre-osteoblast like MC3T3-E1 cells were seeded on PCL scaffold (PCLS), DOPA coated PCL scaffold (PCLSD), and varying concentration of rhBMP2 grafted onto scaffold PCLSD 100, PCLSD 500 (100ng/ml, 500ng/ml loaded), respectively. They were analyzed by cell proliferation, alkaline phosphatase activity, and real time polymerase chain reaction in order to verify an osteogenic activity of cells. Results and Discussion: In results, we demonstrated that our fabricated a hybrid scaffold well coated with DOPA, and enable both only high loading efficiency and sustained release of rhBMP2. In the in vitro results, the developed 3D porous scaffold promoted the pre-osteoblast attachment, cell proliferation. Moreover they encouraged an osteoconductivity compared to rhBMP2-free scaffold. Conclusion: All of results indicated that our manufactured 3D porous scaffold would be useful and potential application for bone tissue engineering field.

The outstanding mechanical response and bone regeneration capacity of robocast dilute magnesium-doped wollastonite scaffolds in critical size bone defects.

The regeneration and repair of damaged load-bearing segmental bones require considerable mechanical strength for the artificial implants. The ideal biomaterials should also facilitate the production of porous implants with high bioactivity desirable for stimulating new bone growth. Here we developed a new mechanically strong, highly bioactive dilute magnesium-doped wollastonite (CaSiO3-Mg; CSi-Mg) porous scaffold by the robocasting technique. The sintered scaffolds had interconnected pores 350 µm in size and over 50% porosity with appreciable compressive strength (>110 MPa), 5-10 times higher than those of pure CSi and β-TCP porous ceramics. Extensive in vitro and in vivo investigations revealed that such Ca-silicate bioceramic scaffolds were particularly beneficial for osteogenic cell activity and osteogenic capacity in critical size femoral bone defects. The CSi-Mg porous constructs were accompanied by an accelerated new bone growth (6-18 weeks) and a mechanically outstanding elastoplastic response to finally match the strength (10-15 MPa) of the rabbit femur host bone after 18 weeks, and the material itself experienced mild resorption and apatite-like phase transformation. In contrast, the new bone regeneration in the β-TCP scaffolds was substantially retarded after 6-12 weeks of implantation, and exhibited a low level of mechanical strength (<10 MPa) similar to the pure CSi scaffolds. These results suggest a promising application of robocast CSi-Mg scaffolds in the clinic, especially for the load-bearing bone defects.

Effect of autogenous and fresh-frozen bone grafts on osteoblast differentiation

ObjectiveFresh-frozen bone allograft (FFBA) is an alternative to autogenous bone (AB) for reconstructing maxillary bone. Despite the promising clinical results, cell responses to FFBA and AB were not evaluated. Thus, our aim was to compare cells harvested from maxillary reconstructed sites with either AB or FFBA in terms of osteoblast differentiation and to evaluate the effect of culturing cells in contact with FFBA. MethodsCells harvested from three patients submitted to bilateral maxillary reconstruction with AB and FFBA were cultured to evaluate: proliferation, alkaline phosphatase activity, extracellular matrix mineralization and gene expression of osteoblastic markers. The effect of FFBA on osteoblast differentiation was studied by culturing cells harvested from AB in contact with FFBA and evaluating the same parameters. Data were compared using either two-way ANOVA followed by Tukey-b test or Student's t test (p≤0.05). ResultsCell proliferation was higher in cultures from AB grafted sites and extracellular matrix mineralization was higher in cultures derived from FFBA grafted sites. The gene expression of alkaline phosphatase, RUNX2, bone sialoprotein and osteocalcin was higher in cells derived from FFBA compared with cells from AB grafted sites. However, the exposure of cells derived from AB to FFBA particles did not have any remarkable effect on osteoblast differentiation. ConclusionsThese results indicate the higher osteogenic activity of cells derived from FFBA compared with AB reconstructed sites, offering an explanation at cellular level of why FFBA could be a suitable alternative to AB for reconstructing maxillary bone defects.