In vitro differentiation of human mesenchymal stem cells on Ti6Al4V surfaces

The Effect of Apple-Derived Nanovesicles on the Osteoblastogenesis of Osteoblastic MC3T3-E1 Cells

Osteoporosis is characterized by low bone mass and elevated structural deterioration of the bone tissue, resulting in bone weakness with an increased risk of fracture. Considering biological activities of various phytochemicals extracted from apples, we herein demonstrated the potential antiosteoporotic effects of apple-derived nanovesicles (apple NVs) using osteoblastic MC3T3-E1 cells. Apple NVs significantly stimulated the growth of MC3T3-E1 cells. The cellular alkaline phosphatase (ALP) activity was significantly upregulated in the 5 μg/mL apple NVs-treated group. In addition, the concentrarion of mineralized nodules was significantly increased in the apple NVs-treated groups. Furthermore, apple NVs increased the expression of the genes and proteins associated with osteoblast growth and differentiation, such as Runx2, ALP, OPN, and BMP2/4, which further activated ERK- and JNK-related mitogen-activated protein kinase signaling. These results demonstrate that apple NVs have a potential to prevent osteoporosis by promoting osteoblastogenesis in osteoblastic MC3T3-E1 cells through regulating the BMP2/Smad1 pathways.

Application of dental stem cells in three-dimensional tissue regeneration

Dental stem cells can differentiate into different types of cells. Dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, stem cells from apical papilla, and dental follicle progenitor cells are five different types of dental stem cells that have been identified during different stages of tooth development. The availability of dental stem cells from discarded or removed teeth makes them promising candidates for tissue engineering. In recent years, three-dimensional (3D) tissue scaffolds have been used to reconstruct and restore different anatomical defects. With rapid advances in 3D tissue engineering, dental stem cells have been used in the regeneration of 3D engineered tissue. This review presents an overview of different types of dental stem cells used in 3D tissue regeneration, which are currently the most common type of stem cells used to treat human tissue conditions.

Effect of porous tantalum on promoting the osteogenic differentiation of bone marrow mesenchymal stem cells in vitro through the MAPK/ERK signal pathway

BACKGROUND

As an ideal new graft material, porous tantalum (pTa) has excellent mechanical properties and corrosion resistance and has received increased attention in the biomedical field because of its excellent cytocompatibility and ability to induce bone formation. However, the molecular mechanism of its potential to promote osteogenesis remains unclear, and very few reports have been published on this topic.

METHODS

In this study, we first produced porous Ti6Al4V (pTi6Al4V) and pTa with the same pore size by three-dimensional printing combined with chemical vapour deposition. The number of adhesions between pTa and pTi6Al4V and bone marrow mesenchymal stem cells (BMSCs) after 1 day of culture was detected by the live/dead cell staining method. The proliferation activity of the two groups was determined after culture for 1, 3, 5 and 7 days by the cell counting kit-8 method. In addition, the osteogenic activity, mRNA expression levels of osteogenic genes alkaline phosphatase (ALP), osterix (OSX), collagen-I (Col-I), osteonectin (OSN) and osteocalcin (OCN) and protein expression levels of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signalling pathway marker p-ERK of the two groups cultured for 7, 14 and 21 days were determined by the ALP activity assay, real-time quantitative polymerase chain reaction (Q-PCR) and Western blotting, respectively. Subsequently, the two groups were treated with the MAPK/ERK-specific inhibitor U0126, and then, the mRNA expression levels of osteogenic genes and protein expression levels of p-ERK in the cultures were determined by Q-PCR and Western blotting, respectively.

RESULTS

The live/dead cell staining and cell counting kit-8 assays showed that the adhesion and proliferation activities of BMSCs on pTa were significantly better than those on pTi6Al4V. In addition, the ALP activity assay and Q-PCR showed that pTa harboured osteogenic activity and that the osteogenic genes ALP, OSX, Col-I, OSN and OCN were highly expressed, and by Western blotting, the expression of p-ERK protein in the pTa group was also significantly higher than that in the pTi6Al4V group. Subsequently, using the MAPK/ERK-specific inhibitor U0126, Western blotting showed that the expression of p-ERK protein was significantly inhibited and that there was no difference between the two groups. Furthermore, Q-PCR showed that osteogenic gene expression and ALP expression levels were significantly increased in the pTa group, and there were no differences in the OSX, Col-I, OSN and OCN mRNA expression levels between the two groups.

CONCLUSION

Overall, our research found that compared with the widely used titanium alloy materials, our pTa can promote the adhesion and proliferation of BMSCs, and the molecular mechanism of pTa may occur via activation of the MAPK/ERK signalling pathway to regulate the high expression of OSX, Col I, OSN and OCN osteogenic genes and promote the osteogenic differentiation of BMSCs in vitro. The translational potential of this article : Our self-developed pTa material produced by three-dimensional printing combined with the chemical vapour deposition method not only retains excellent biological activity and osteoinductive ability of the original tantalum metal but also saves considerably on material costs to achieve mass production of personalised orthopaedic implants with pTa as a stent and to accelerate the wide application of pTa implants in clinical practice, which have certain profound significance.

Adipose stem cells for bone tissue repair

Adipose-derived stem/stromal cells (ASCs), together with adipocytes, vascular endothelial cells, and vascular smooth muscle cells, are contained in fat tissue. ASCs, like the human bone marrow stromal/stem cells (BMSCs), can differentiate into several lineages (adipose cells, fibroblast, chondrocytes, osteoblasts, neuronal cells, endothelial cells, myocytes, and cardiomyocytes). They have also been shown to be immunoprivileged, and genetically stable in long-term cultures. Nevertheless, unlike the BMSCs, ASCs can be easily harvested in large amounts with minimal invasive procedures. The combination of these properties suggests that these cells may be a useful tool in tissue engineering and regenerative medicine.

Stem cells applications in bone and tooth repair and regeneration: New insights, tools, and hopes

The exploration of stem and progenitor cells holds promise for advancing our understanding of the biology of tissue repair and regeneration mechanisms after injury. This will also help in the future use of stem cell therapy for the development of regenerative medicine approaches for the treatment of different tissue-species defects or disorders such as bone, cartilages, and tooth defects or disorders. Bone is a specialized connective tissue, with mineralized extracellular components that provide bones with both strength and rigidity, and thus enable bones to function in body mechanical supports and necessary locomotion process. New insights have been added to the use of different types of stem cells in bone and tooth defects over the last few years. In this concise review, we briefly describe bone structure as well as summarize recent research progress and accumulated information regarding the osteogenic differentiation of stem cells, as well as stem cell contributions to bone repair/regeneration, bone defects or disorders, and both restoration and regeneration of bones and cartilages. We also discuss advances in the osteogenic differentiation and bone regeneration of dental and periodontal stem cells as well as in stem cell contributions to dentine regeneration and tooth engineering.

Infection and Pulp Regeneration

The regeneration of the pulp-dentin complex has been a great challenge to both scientists and clinicians. Previous work has shown that the presence of prior infection may influence the characteristics of tissues formed in the root canal space after regenerative endodontic treatment. The formation of ectopic tissues such as periodontal ligament, bone, and cementum has been observed in the root canal space of immature necrotic teeth with apical periodontitis, while the regeneration of dentin and pulp has been identified in previously non-infected teeth.  The current regenerative endodontic therapy utilizes disinfection protocols, which heavily rely on chemical irrigation using conventional disinfectants. From a microbiological point of view, the current protocols may not allow a sufficiently clean root canal microenvironment, which is critical for dentin and pulp regeneration. In this article, the significance of root canal disinfection in regenerating the pulp-dentin complex, the limitations of the current regenerative endodontic disinfection protocols, and advanced disinfection techniques designed to reduce the microorganisms and biofilms in chronic infection are discussed.

Osteogenic differentiation of adipose tissue-derived mesenchymal stem cells on nanostructured Ti6Al4V and Ti13Nb13Zr

Bone tissue engineering and nanotechnology enable the design of suitable substitutes to restore and maintain the function of human bone tissues in complex fractures and other large skeletal defects. Long-term stability and functionality of prostheses depend on integration between bone cells and biocompatible implants. Human adipose tissue-derived mesenchymal stem cells (hAMSCs) have been shown to possess the same ability to differentiate into osteoblasts and to produce bone matrix of classical bone marrow derived stem cells (BMMSCs). Ti6A14V and Ti13Nb13Zr are two different biocompatible titanium alloys suitable for medical bone transplantation. Preliminary results from our Research Group demonstrated that smooth Ti6Al4V surfaces exhibit an osteoconductive action on hAMSCs, granting their differentiation into functional osteoblasts and sustaining bone matrix synthesis and calcification. The purpose of this study is to assay the ability of nanostructured Ti6Al4V and Ti13Nb13Zr alloys to preserve the growth and adhesion of hAMSCs and, mostly, to sustain and maintain their osteogenic differentiation and osteoblast activity. The overall results showed that both nanostructured titanium alloys are capable of sustaining cell adhesion and proliferation, to promote their differentiation into osteoblast lineage, and to support the activity of mature osteoblasts in terms of calcium deposition and bone extracellular matrix protein production.

In Vitro Behavior of Human Adipose Tissue-Derived Stem Cells on Poly(ε-caprolactone) Film for Bone Tissue Engineering Applications

Bone tissue engineering is an emerging field, representing one of the most exciting challenges for scientists and clinicians. The possibility of combining mesenchymal stem cells and scaffolds to create engineered tissues has brought attention to a large variety of biomaterials in combination with osteoprogenitor cells able to promote and regenerate bone tissue. Human adipose tissue is officially recognized as an easily accessible source of mesenchymal stem cells (AMSCs), a significant factor for use in tissue regenerative medicine. In this study, we analyze the behavior of a clonal finite cell line derived from human adipose tissue seeded on poly(ε-caprolactone) (PCL) film, prepared by solvent casting. PCL polymer is chosen for its good biocompatibility, biodegradability, and mechanical properties. We observe that AMSCs are able to adhere to the biomaterial and remain viable for the entire experimental period. Moreover, we show that the proliferation process and osteogenic activity of AMSCs are maintained on the biofilm, demonstrating that the selected biomaterial ensures cell colonization and the development of an extracellular mineralized matrix. The results of this study highlight that AMSCs and PCL film can be used as a suitable model to support regeneration of new bone for future tissue engineering strategies.

In Vitro Effects of Strontium on Proliferation and Osteoinduction of Human Preadipocytes

Development of tools to be used for in vivo bone tissue regeneration focuses on cellular models and differentiation processes. In searching for all the optimal sources, adipose tissue-derived mesenchymal stem cells (hADSCs or preadipocytes) are able to differentiate into osteoblasts with analogous characteristics to bone marrow mesenchymal stem cells, producing alkaline phosphatase (ALP), collagen, osteocalcin, and calcified nodules, mainly composed of hydroxyapatite (HA). The possibility to influence bone differentiation of stem cells encompasses local and systemic methods, including the use of drugs administered systemically. Among the latter, strontium ranelate (SR) represents an interesting compound, acting as an uncoupling factor that stimulates bone formation and inhibits bone resorption. The aim of our study was to evaluate the in vitro effects of a wide range of strontium (Sr(2+)) concentrations on proliferation, ALP activity, and mineralization of a novel finite clonal hADSCs cell line, named PA20-h5. Sr(2+) promoted PA20-h5 cell proliferation while inducing the increase of ALP activity and gene expression as well as HA production during in vitro osteoinduction. These findings indicate a role for Sr(2+) in supporting bone regeneration during the process of skeletal repair in general, and, more specifically, when cell therapies are applied.

Human Preosteoblastic Cell Culture from a Patient with Severe Tumoral Calcinosis-Hyperphosphatemia Due to a New GALNT3 Gene Mutation: Study of In Vitro Mineralization

Human disorders of phosphate (Pi) handling and skeletal mineralization represent a group of rare bone diseases. One of these disease is tumoral calcinosis (TC). In this study, we present the case of a patient with TC with a new GALNT3 gene mutation. We also performed functional studies using an in vitro cellular model. Genomic DNA was extracted from peripheral blood collected from a teenage Caucasian girl affected by TC, and from her parents. A higher capability to form mineralization nodules in vitro was found in human preosteoblastic cells of mutant when compared to wild-type controls. We found a novel homozygous inactivating splice site mutation in intron I (c.516-2a>g). A higher capability to form mineralization nodules in vitro was found in the mutant cells in human preosteoblastic cells when compared to wild-type controls. Understanding the functional significance and molecular physiology of this novel mutation will help to define the role of FGF23 in the control of Pi homeostasis in normal and in pathological conditions.

Ultraviolet irradiation enhanced bioactivity and biological response of mesenchymal stem cells on micro-arc oxidized titanium surfaces

This present study investigated the effect of ultraviolet (UV) irradiation on bioactivity of micro-arc oxidized (MAO) titanium surface in vitro by cell culture medium immersion test and interactions with rat-derived mesenchymal stem cells (MSCs). UV-irradiated MAO surface exhibited no obvious changes in surface roughness, morphology, and phase composition when compared with MAO-only surface. However, in cell culture medium immersion test, markedly more bone-like apatite was formed on UV-modified samples than on MAO sample. Rat bone marrow- and adipose tissue-derived MSCs cultured on UV-modified samples displayed accelerated attachment, significant higher levels of alkaline phosphatase (ALP) activity, and up-regulated osteogenesis-related mRNA expression than MAO sample. XPS results provided direct evidence that the amount of basic hydroxyl groups increased with UV irradiation time, which could be one of the key mechanisms underlying their improved bioactivity.

Universality of the network-dynamics of the cell nucleus at high frequencies

The interior of the cell nucleus is comparable to a solid network bathed in an interstitial fluid. From the extrapolation of low frequency data, it is expected that such network should dictate the response of the nucleus to mechanical stress at high frequencies, described by unique elastic moduli. However, none of the existing techniques that can probe the mechanical properties of cells can exceed the kHz range, and the mechanics of the nuclear network remain poorly understood. We use laser-generated acoustic waves to probe remotely the stiffness and viscosity of nuclei in single cells in the previously unexplored GHz range with a ∼100 nm axial resolution. The probing of cells at contrasted differentiation stages, ranging from stem cells to mature cells originating from different tissues, demonstrates that the mechanical properties of the nuclear network are common across various cell types. This points to an asymptotically increasing influence of a solid meshwork of connected chromatin fibers.

Adipose mesenchymal stem cells in the field of bone tissue engineering

Bone tissue engineering represents one of the most challenging emergent fields for scientists and clinicians. Current failures of autografts and allografts in many pathological conditions have prompted researchers to find new biomaterials able to promote bone repair or regeneration with specific characteristics of biocompatibility, biodegradability and osteoinductivity. Recent advancements for tissue regeneration in bone defects have occurred by following the diamond concept and combining the use of growth factors and mesenchymal stem cells (MSCs). In particular, a more abundant and easily accessible source of MSCs was recently discovered in adipose tissue. These adipose stem cells (ASCs) can be obtained in large quantities with little donor site morbidity or patient discomfort, in contrast to the invasive and painful isolation of bone marrow MSCs. The osteogenic potential of ASCs on scaffolds has been examined in cell cultures and animal models, with only a few cases reporting the use of ASCs for successful reconstruction or accelerated healing of defects of the skull and jaw in patients. Although these reports extend our limited knowledge concerning the use of ASCs for osseous tissue repair and regeneration, the lack of standardization in applied techniques makes the comparison between studies difficult. Additional clinical trials are needed to assess ASC therapy and address potential ethical and safety concerns, which must be resolved to permit application in regenerative medicine.

High-Frequency Vibration Treatment of Human Bone Marrow Stromal Cells Increases Differentiation toward Bone Tissue

In order to verify whether differentiation of adult stem cells toward bone tissue is promoted by high-frequency vibration (HFV), bone marrow stromal cells (BMSCs) were mechanically stimulated with HFV (30 Hz) for 45 minutes a day for 21 or 40 days. Cells were seeded in osteogenic medium, which enhances differentiation towards bone tissue. The effects of the mechanical treatment on differentiation were measured by Alizarin Red test, (q) real-time PCR, and protein content of the extracellular matrix. In addition, we analyzed the proliferation rate and apoptosis of BMSC subjected to mechanical stimulation. A strong increase in all parameters characterizing differentiation was observed. Deposition of calcium was almost double in the treated samples; the expression of genes involved in later differentiation was significantly increased and protein content was higher for all osteogenic proteins. Lastly, proliferation results indicated that stimulated BMSCs have a decreased growth rate in comparison with controls, but both treated and untreated cells do not enter the apoptosis process. These findings could reduce the gap between research and clinical application for bone substitutes derived from patient cells by improving the differentiation protocol for autologous cells and a further implant of the bone graft into the patient.

Osteodifferentiation of human preadipocytes induced by strontium released from hydrogels

In recent years, there has been an increasing interest in interactive application principles of biology and engineering for the development of valid biological systems for tissue regeneration, such as for the treatment of bone fractures or skeletal defects. The application of stem cells together with biomaterials releasing bioactive factors promotes the formation of bone tissue by inducing proliferation and/or cell differentiation. In this study, we used a clonal cell line from human adipose tissue-derived mesenchymal stem cells (hADSCs or preadipocytes), named PA2-E12, to evaluate the effects of strontium (Sr²⁺) released in the culture medium from an amidated carboxymethylcellulose (CMCA) hydrogel enriched with different Sr²⁺ concentrations on osteodifferentiation. The osteoinductive effect was evaluated through both the expression of alkaline phophatase (ALP) activity and the hydroxyapatite (HA) production during 42 days of induction. Present data have shown that Sr²⁺ released from CMCA promotes the osteodifferentiation induced by an osteogenic medium as shown by the increase of ALP activity at 7 and 14 days and of HA production at 14 days. In conclusion, the use of biomaterials able to release in situ osteoinductive agents, like Sr²⁺, could represent a new strategy for future applications in bone tissue engineering.

Mesenchymal stem cells as a potent cell source for bone regeneration

While small bone defects heal spontaneously, large bone defects need surgical intervention for bone transplantation. Autologous bone grafts are the best and safest strategy for bone repair. An alternative method is to use allogenic bone graft. Both methods have limitations, particularly when bone defects are of a critical size. In these cases, bone constructs created by tissue engineering technologies are of utmost importance. Cells are one main component in the manufacture of bone construct. A few cell types, including embryonic stem cells (ESCs), adult osteoblast, and adult stem cells, can be used for this purpose. Mesenchymal stem cells (MSCs), as adult stem cells, possess characteristics that make them good candidate for bone repair. This paper discusses different aspects of MSCs that render them an appropriate cell type for clinical use to promote bone regeneration.

Osteogenesis of human mesenchymal stem cells on micro-patterned surfaces

Osteogenic responses of human mesenchymal stromal cells (hMSCs) were compared on square-patterned, inverse square-patterned, and planar titanium, chromium, diamond-like carbon (DLC), and tantalum; hypothesis was that both the materials and patterns affect osteogenesis. Samples were produced using photolithography and physical vapor deposition. Early-marker alkaline phosphatase (ALP) and mid-markers, small body size and mothers against decapentaplegic-related protein-1 (SMAD1), runt-related transcription factor-2 (RUNX2), and osteopontin were studied using quantitative real-time polymerase chain reaction. ALP and hydroxyapatite, were colorimetrically studied. ALP reached highest values on both patterned titanium samples, but mid-markers disclosed that it was already lagging behind planar and inverse patterned tantalum. Hydroxyapatite formation disclosed that osteo-induced hMSCs passed all the differentiation stages (except on planar chromium). Presence of hydroxyapatite disclosed that both types of patterning promoted ( p < 0.001) osteogenesis compared to planar samples. Results suggest that the osseocompatibility/integration of implants could be improved by changing the monotonous and featureless implant–host interface into micro-patterned interface to provide physical differentiation cues.

Recent highlights on bone stem cells: a report from Bone Stem Cells 2009, and not only…

The use of stem cells has opened new prospects for the treatment of orthopaedic conditions characterized by large bone defects. However, many issues still exist to which answers are needed before routine, large-scale application becomes possible. Bone marrow stromal cells (MSC), which are clonogenic, multipotential precursors present in the bone marrow stroma, are generally employed for bone regeneration. Stem cells with multilineage differentiation similar to MSC have also been demonstrated in adipose tissue, peripheral blood, umbilical cord and amniotic fluid. Each source presents its own advantages and drawbacks. Unfortunately, no unique surface antigen is expressed by MSC, and this hampers simple MSC enrichment from heterogeneous populations. MSC are identified through a combination of physical, morphological and functional assays. Different in vitro and in vivo models have been described for the research on bone stem cells. These models should predict the in vivo bone healing capacity of MSC and if the induced osteogenesis is similar to the physiological one. Although stem cells offer an exciting possibility of a renewable source of cells and tissues for replacement, orthopaedic applications often represent case reports whereas controlled randomized trials are still lacking. Further biological aspects of bone stem cells should be elucidated and a general consensus on the best models, protocols and proper use of scaffolds and growth factors should be achieved.

In vitro osteoblastic differentiation of human mesenchymal stem cells and human dental pulp stem cells on poly-L-lysine-treated titanium-6-aluminium-4-vanadium

Three-dimensional (3D) titanium-6-aluminium-4-vanadium (Ti6Al4V) is a widely used biomaterial for orthopedic prosthesis and dental implants; thanks to its very high-mechanical strength and resistance to corrosion. Human mesenchymal stem cells (hMSCs) and dental pulp stem cells (hDPSCs) are responsible for bone regeneration following colonization of prosthesis or dental implants. Both hMSCs and hDPSCs have lower ability to colonize this biomaterial in comparison with tissue culture-treated plastic. Both hMSCs and hDPSCs show lack of focal adhesion kinase (FAK) activation when grown on Ti6Al4V. This signal is restored in the presence of poly-L-lysine (poly-L-lys). Poly-L-lys has been used as part of organoapatite or together with zinc and calcium ions. Our results suggest that poly-L-lys alone induces FAK activation through β1-INTEGRIN, because the presence of β1-INTEGRIN blocking antibody avoided FAK autophosphorylation. Presence of poly-L-lys also increases expression of osteoblastic differentiation marker genes in hMSCs and hDPSCs grown on Ti6Al4V.

Stimulated osteoblastic proliferation by mesoporous silica xerogel with high specific surface area

Specific surface area is a critical parameter of mesoporous silica-based biomaterials, however, little is known about its effects on osteoblast responses in vitro. In the present study, mesoporous silica xerogels (MSXs) with different surface area (401, 647 and 810 m(2)/g, respectively) were synthesized by a sol-gel process. Surface silanol contents decreased with the increase of surface area with which protein adsorption capability positively correlated. And the apatite-like surface seemed to form faster on MSXs with higher surface area determined by XRD analysis. Using MG63 osteoblast-like cells as models, it was found that cell proliferations were promoted on MSXs with higher surface area, based on the premise that the effects of Si released from materials on osteoblast viability were excluded by real-time Transwell(®) assay. RT-PCR results indicated cell adhesion-related integrin subunits α5 were up-regulated by higher surface area at day 1, which was further confirmed by flow cytometry analysis. The data suggest that increasing SSA of MSXs could promote surface cellular affinity by adsorbing serum proteins and accelerating apatite-like layer formation, which results in promoted osteoblastic proliferation via integrin subunit α5 at initial adhesion stage. Regulating SSA, an effective approach in designing mesoporous silica-based materials, provides an alternative method to obtain desirable tissue-response in bone regeneration and drug-delivery system.

Effects of Dicalcium Silicate Coating Ionic Dissolution Products on Human Mesenchymal Stem-Cell Proliferation and Osteogenic Differentiation

This study investigated the effects of ionic dissolution products released from dicalcium silicate (DS) coatings on human mesenchymal stem cells (hMSC), cultured in the presence or absence of the dissolution products, with or without osteogenic supplements (OS). DS+ medium promoted cell proliferation during the first 4 days, but then inhibited proliferation. DS+OS− medium increased alkaline phosphatase (ALP) activity on day 14, and upregulated runt-related transcription factor 2 and osteonectin mRNA on days 7 and 14, respectively. The addition of osteogenic supplements (DS+OS+) led to a significant increase in ALP activity from days 7 to 21, upregulation of osteogenic markers on day 14, and formation of more mineralized nodules on day 28. The results demonstrated that the ionic dissolution products from DS coating alone can partly induce osteogenic differentiation of hMSC, and that the addition of osteogenic supplements further enhances osteoblast-specific gene expression and mineralization in hMSC.

Preliminary evaluation of a novel strong/osteoinductive calcium phosphate cement

We developed a novel calcium phosphate cement (CPC) by combining the silk fibroin and osteogenic supplements (β-glycerophosphate, ascorbic acid, and dexamethasone) with α-tricalcium phosphate cement. Mesenchymal stem cells (MSCs) were cultured on the novel CPC scaffold. Results showed that the novel CPC scaffold was biocompatible and favorable for the adhesion, spreading, and proliferation of MSCs. Osteogenic differentiation of MSCs was confirmed by high osteocalcin content and elevated gene expressions of bone markers, such as alkaline phosphatase, collagen type I, and osteocalcin. Therefore, the novel CPC scaffold may be potentially useful for implant fixation and more rapid new bone formation in moderate load-bearing applications.

Response of human bone marrow stromal cells to a novel ultra-fine-grained and dispersion-strengthened titanium-based material

A novel titanium-based material, containing no toxic or expensive alloying elements, was compared to the established biomaterials: commercially pure titanium (c.p.Ti) and Ti6Al4V. This material (Ti/1.3HMDS) featured similar hardness, yield strength and better wear resistance than Ti6Al4V, as well as better electrochemical properties at physiological pH7.4 than c.p.Ti grade 1 of our study. These excellent properties were obtained by utilizing an alternative mechanism to produce a microstructure of very fine titanium silicides and carbides (<100 nm) embedded in an ultra-fine-grained Ti matrix (365 nm). The grain refinement was achieved by high-energy ball milling of Ti powder with 1.3 wt.% of hexamethyldisilane (HMDS). The powder was consolidated by spark plasma sintering at moderate temperatures of 700 degrees C. The microstructure was investigated by optical and scanning electron microscopy (SEM) and correlated to the mechanical properties. Fluorescence microscopy revealed good adhesion of human mesenchymal stem cells on Ti/1.3HMDS comparable to that on c.p.Ti or Ti6Al4V. Biochemical analysis of lactate dehydrogenase and specific alkaline phosphatase activities of osteogenically induced hMSC exhibited equal proliferation and differentiation rates in all three cases. Thus the new material Ti/1.3HMDS represents a promising alternative to the comparatively weak c.p.Ti and toxic elements containing Ti6Al4V.

Biomaterials in orthopaedics

At present, strong requirements in orthopaedics are still to be met, both in bone and joint substitution and in the repair and regeneration of bone defects. In this framework, tremendous advances in the biomaterials field have been made in the last 50 years where materials intended for biomedical purposes have evolved through three different generations, namely first generation (bioinert materials), second generation (bioactive and biodegradable materials) and third generation (materials designed to stimulate specific responses at the molecular level). In this review, the evolution of different metals, ceramics and polymers most commonly used in orthopaedic applications is discussed, as well as the different approaches used to fulfil the challenges faced by this medical field.

Therapeutic potential of stem cells in skin repair and regeneration

Stem cells are defined by their capacity of self-renewal and multilineage differentiation, which make them uniquely situated to treat a broad spectrum of human diseases. Based on a series of remarkable studies in several fields of regenerative medicine, their application is not too far from the clinical practice. Full-thickness burns and severe traumas can injure skin and its appendages, which protect animals from water loss, temperature change, radiation, trauma and infection. In adults, the normal outcome of repair of massive full-thickness burns is fibrosis and scarring without any appendages, such as hair follicles, sweat and sebaceous glands. Perfect skin regeneration has been considered impossible due to the limited regenerative capacity of epidermal keratinocytes, which are generally thought to be the key source of the epidermis and skin appendages. Currently, researches on stem cells, such as epidermal stem cells, dermal stem cells, mesenchymal stem cells from bone marrow, and embryonic stem cells, bring promise to functional repair of skin after severe burn injury, namely, complete regeneration of skin and its appendages. In this study, we present an overview of the most recent advances in skin repair and regeneration by using stem cells.