Electrosprayed hydroxyapatite on polymer nanofibers to differentiate mesenchymal stem cells to osteogenesis.

Electrospraying of hydroxyapatite (HA) nanoparticles onto the surface of polymer nanofibers provides a potentially novel substrate for the adhesion, proliferation and differentiation of mesenchymal stem cells (MSCs) into bone tissue regeneration. HA nanoparticles (4%) were electrosprayed on the surface of electrospun polycaprolactone (PCL) nanofibers (420 ± 15 nm) for bone tissue engineering. PCL/HA nanofibers were comparatively characterized with PCL/Collagen (275 ± 56 nm) nanofibers by FT-IR analysis to confirm the presence of HA. Fabricated PCL/HA and PCL/Collagen nanofibers and TCP (control) were used for the differentiation of equine MSC into osteogenic lineages in the presence of DMEM/F12 medium supplemented with ß-glycerophosphate, ascorbic acid and dexamethasone. Cell proliferation and differentiation into an osteogenic lineage was evaluated by MTS assay, SEM observation, ALP activity, ARS staining, quantification of mineral deposition and expression of osteocalcin. Proliferation of MSCs increased significantly (P ⩽ 0.05) up to 12% in PCL/Collagen (day 15) compared to PCL/HA nanofibrous substrate. ALP activity was increased 20% in PCL/HA by day 10 confirming the direction of osteogenic lineage from MSCs differentiation. PCL/HA stimulated an increased mineral secretion up to 26% by day 15 on ARS staining compared to PCL/Collagen nanofibers and showing cuboidal morphology by expressing osteocalcin. These results confirmed that the specifically fabricated PCL/HA composite nanofibrous substrate enhanced the differentiation of MSCs into osteogenesis.

The use of HE4 in the prediction of ovarian cancer in Asian women with a pelvic mass.

OBJECTIVE: The purpose of this study was to evaluate the performance of human epididymis protein 4 (HE4) and the Risk of Ovarian Malignancy Algorithm (ROMA) for distinguishing between benign and malignant pelvis masses in Asian women. METHODS: This was a prospective, multicenter (n=6) study with patients from six Asian countries. Patients had a pelvic mass on imaging and were scheduled to undergo surgery. Serum CA125 and HE4 were measured on preoperative samples. CA125, HE4, and ROMA were evaluated for sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). RESULTS: A total of 414 women with an adnexal mass were evaluated, of which 65 had epithelial ovarian (EOC) cancer, 16 had borderline tumors and 11 had other malignant diseases. Compared to CA125, HE4 had lower sensitivity (56.9% vs 90.8%) and NPV (91.8% vs 97.3%), but improved specificity (96.9% vs 67.1%) and PPV (78.7% vs 35.8%) for differentiating between benign pelvic mass and EOC. ROMA had similar sensitivity (89.2% vs 90.8%) and NPV (97.6% vs 97.3%) as CA125, but showed improved specificity (87.3% vs 67.1%) and PPV (58.6% vs 35.8%). ROMA accurately predicted 87.3% of benign cases as low risk, and 82.6% of stage I/II EOC and 89.2% of all EOC as high risk. CONCLUSION: ROMA showed similar sensitivity as CA125 but improved specificity and PPV, especially in premenopausal women. Using ROMA may help predict if a pelvic mass is benign or malignant and facilitate subsequent management planning.

Biomimetic hydroxyapatite-containing composite nanofibrous substrates for bone tissue engineering.

The fracture of bones and large bone defects owing to various traumas or natural ageing is a typical type of tissue malfunction. Surgical treatment frequently requires implantation of a temporary or permanent prosthesis, which is still a challenge for orthopaedic surgeons, especially in the case of large bone defects. Mimicking nanotopography of natural extracellular matrix (ECM) is advantageous for the successful regeneration of damaged tissues or organs. Electrospun nanofibre-based synthetic and natural polymer scaffolds are being explored as a scaffold similar to natural ECM for tissue engineering applications. Nanostructured materials are smaller in size falling, in the 1-100 nm range, and have specific properties and functions related to the size of the natural materials (e.g. hydroxyapatite (HA)). The development of nanofibres with nano-HA has enhanced the scope of fabricating scaffolds to mimic the architecture of natural bone tissue. Nanofibrous substrates supporting adhesion, proliferation, differentiation of cells and HA induce the cells to secrete ECM for mineralization to form bone in bone tissue engineering. Our laboratory (NUSNNI, NUS) has been fabricating a variety of synthetic and natural polymer-based nanofibrous substrates and synthesizing HA for blending and spraying on nanofibres for generating artificial ECM for bone tissue regeneration. The present review is intended to direct the reader's attention to the important subjects of synthetic and natural polymers with HA for bone tissue engineering.

Continuous nanostructures for the controlled release of drugs.

The annual world wide market for controlled release of polymer systems which extends beyond drug delivery is now estimated to $60 billion and these systems are used by over 100 million people each year. It was estimated that drug delivery will play a pivotal role in approximately 40% of all pharmaceutical sales in near future. Novel methods of drug delivery will not only result in more effective and efficacious treatments but also generates new niche markets to provide greater intellectual property protection to already existing drug formulations. Recently, biodegradable electrospun polymer nanofibrous substrate as drug carrier seems to be a promising method for delivering anticancer drugs, especially in postoperative local chemotherapy. Alternatively drug release can be triggered by the environment or other external events such as changes in pH, temperature, or the presence of analyte such as glucose. In general, controlled release of polymer systems delivering drugs in the optimum dosage for long periods is to increase the efficacy of drug, reducing patient compliance. Recent research for the use of nanotechnology (nanoparticle and nanofibers) in drug delivery suggests that the technology might solve problems in the areas such as controlled release, various topical administration, gut absorption and targeted systemic delivery. This review article described the applications of polymer nanoparticles and nanofibers for loading potential drugs for the controlled release to target incurable diseases.

Aligned and random nanofibrous substrate for the in vitro culture of Schwann cells for neural tissue engineering.

The current challenge in peripheral nerve tissue engineering is to produce an implantable scaffold capable of bridging long nerve gaps that will produce results similar to autograft without requiring the harvest of autologous donor tissue. Aligned and random polycaprolactone/gelatin (PCL/gelatin) nanofibrous scaffolds were fabricated for the in vitro culture of Schwann cells that assist in directing the growth of regenerating axons in nerve tissue engineering. The average fiber diameter attained by electrospinning of polymer blend (PCL/gelatin) ranged from 232+/-194 to 160+/-86nm with high porosity (90%). Blending PCL with gelatin resulted in increased hydrophilicity of nanofibrous scaffolds and yielded better mechanical properties, approaching those of PCL nanofibers. The biocompatibility of fabricated nanofibers was assessed for culturing and proliferation of Schwann cells by MTS assay. The results of the MTS assay and scanning electron microscopy confirmed that aligned and random PCL/gelatin nanofibrous scaffolds are suitable substrates for Schwann cell growth as compared to PCL nanofibrous scaffolds for neural tissue engineering.

Nanotechnology for nanomedicine and delivery of drugs.

Nanotechnology is an emerging technology seeking to exploit distinct technological advances controlling the structure of materials at a reduced dimensional scale approaching individual molecules and their aggregates or supramolecular structures. The manipulation and utilization of materials at nanoscale are expected to be critical drivers of economic growth and development in this century. In recent years, nanoscale sciences and engineering have provided new avenues for engineering materials down to molecular scale precision. The resultant materials have been demonstrated to have enhanced properties and applicability; and these materials are expected to be enabling technologies in the successful development and application of nanomedicine. Nanomedicine is defined as the monitoring, repair, construction, and control of human biological systems at the molecular level using engineered nanodevices and nanostructures. Electrospinning is a simple and cost-effective technique, capable of producing continuous fibers of various materials from polymers to ceramics. The electrospinning technique is used for the preparation of nanofibers and macroporous scaffolds intended for drug delivery and tissue engineering. These have special characteristics in terms of fabrication, porosity, variable diameters, topology and mechanical properties. This review summarizes the recent developments in utilizing nanofibers for drug delivery and tissue engineering applications.

Nanobioengineered electrospun composite nanofibers and osteoblasts for bone regeneration.

Bone defects represent a medical and socioeconomic challenge. Engineering bioartificial bone tissues may help to solve problems related to donor site morbidity and size limitations. Nanofibrous scaffolds were electrospun into a blend of synthetic biodegradable polycaprolactone (PCL) with hydroxyapatite (HA) and natural polymer gelatin (Gel) at a ratio of 1:1:2 (PCL/HA/Gel) compared to PCL (9%), PCL/HA (1:1), and PCL/Gel (1:2) nanofibers. These fiber diameters were around 411 +/- 158 to 856 +/- 157 nm, and the pore size and porosity around 5-35 microm and 76-93%, respectively. The interconnecting porous structure of the nanofibrous scaffolds provides large surface area for cell attachment and sufficient space for nutrient transportation. The tensile property of composite nanofibrous scaffold (PCL/HA/Gel) was highly flexible and allows penetrating osteoblasts inside the scaffolds for bone tissue regeneration. Fourier transform infrared analysis showed that the composite nanofiber contains an amino group, a phosphate group, and carboxyl groups for inducing proliferation and mineralization of osteoblasts for in vitro bone formation. The cell proliferation (88%), alkaline phosphatase activity (77%), and mineralization (66%) of osteoblasts were significantly (P < 0.001) increased in composite nanofibrous scaffold compared to PCL nanofibrous scaffolds. Field emission scanning electron microscopic images showed that the composite nanofibers supported the proliferation and mineralization of osteoblast cells. These results show that the fabrication of electrospun PCL/HA/Gel composite nanofibrous scaffolds has potential for the proliferation and mineralization of osteoblasts for bone regeneration.

Electrospun-modified nanofibrous scaffolds for the mineralization of osteoblast cells.

Biocompatible polycaprolactone (PCL) and hydroxyapatite (HA) were fabricated into nanofibrous scaffolds for the mineralization of osteoblasts in bone tissue engineering. PCL and PCL/HA nanofibrous surface were modified using oxygen plasma treatment and showing 0 degrees contact angle for the adhesion and mineralization of osteoblast cells. The fiber diameter, pore size and porosity of nanofibrous scaffolds were estimated to be 220-625 nm, 3-20 microm, and 87-92% respectively. The ultimate tensile strength of PCL was about 3.37 MPa and PCL/HA was 1.07 MPa to withstand the long term culture of osteoblasts on nanofibrous scaffolds. Human fetal osteoblast cells (hFOB) were cultured on PCL and PCL/HA surface modified and unmodified nanofibrous scaffolds. The osteoblast proliferation rate was significantly (p < 0.001) increased in surface-modified nanofibrous scaffolds. FESEM showed normal phenotypic cell morphology and mineralization occurred in PCL/HA nanofibrous scaffolds, HA acting as a chelating agent for the mineralization of osteoblast to form bone like apatite for bone tissue engineering. EDX and Alizarin Red-S staining indicated mineral Ca(2+) and phosphorous deposited on the surface of osteoblast cells. The mineralization was significantly increased in PCL/HA-modified nanofibrous scaffolds and appeared as a mineral nodule synthesized by osteoblasts similar to apatite of the natural bone. The present study indicated that the PCL/HA surface-modified nanofibrous scaffolds are potential for the mineralization of osteoblast for bone tissue engineering.

Interaction of cells and nanofiber scaffolds in tissue engineering.

Nanofibers and nanomaterials are potentially recent additions to materials in relation to tissue engineering (TE). TE is the regeneration of biological tissues through the use of cells, with the aid of supporting structures and biomolecules. Mimicking architecture of extracellular matrix is one of the challenges for TE. Biodegradable biopolymer nanofibers with controlled surface and internal molecular structures can be electrospun into mats with specific fiber arrangement and structural integrity for drug delivery and TE applications. The polymeric materials are widely accepted because of their ease of processability and amenability to provide a large variety of cost-effective materials, which help to enhance the comfort and quality of life in modern biomedical and industrial society. Today, nanotechnology and nanoscience approaches to scaffold design and functionalization are beginning to expand the market for drug delivery and TE is forming the basis for highly profitable niche within the industry. This review describes recent advances for fabrication of nanofiber scaffolds and interaction of cells in TE.

Mineralization of osteoblasts with electrospun collagen/hydroxyapatite nanofibers.

Regeneration of fractured or diseased bones is the challenge faced by current technologies in tissue engineering. The major solid components of human bone consist of collagen and hydroxyapatite. Collagen (Col) and hydroxyapatite (HA) have potential in mimicking natural extracellular matrix and replacing diseased skeletal bones. More attention has been focused on HA because of its crystallographic structure similar to inorganic compound found in natural bone and extensively investigated due to its excellent biocompatibility, bioactivity and osteoconductivity properties. In the present study, electrospun nanofibrous scaffolds are fabricated with collagen (80 mg/ml) and Col/HA (1:1). The diameter of the collagen nanofibers is around 265 +/- 0.64 nm and Col/HA nanofibers are 293 +/- 1.45 nm. The crystalline HA (29 +/- 7.5 nm) loaded into the collagen nanofibers are embedded within nanofibrous matrix of the scaffolds. Osteoblasts cultured on both scaffolds and show insignificant level of proliferation but mineralization was significantly (p < 0.001) increased to 56% in Col/HA nanofibrous scaffolds compared to collagen. Energy dispersive X-ray analysis (EDX) spectroscopy results proved the presence of higher level of calcium and phosphorous in Col/HA nanocomposites than collagen nanofibrous scaffolds grown osteoblasts. The results of the present study suggested that the designed electrospun nanofibrous scaffold (Col/HA) have potential biomaterial for bone tissue engineering.