Engineered Zero-Dimensional Fullerene/Carbon Dots-Polymer Based Nanocomposite Membranes for Wastewater Treatment.

With the rapid growth of industrialization, diverse pollutants produced as by-products are emitted to the air-water ecosystem, and toxic contamination of water is one of the most hazardous environmental issues. Various forms of carbon have been used for adsorption, electrochemical, and ion-exchange membrane filtration to separation processes for water treatment. The utilization of carbon materials has gained tremendous attention as they have exceptional properties such as chemical, mechanical, thermal, antibacterial activities, along with reinforcement capability and high thermal stability, that helps to maintain the ecological balance. Recently, engineered nano-carbon incorporated with polymer as a composite membrane has been spotlighted as a new and effective mode for water treatment. In particular, the properties of zero-dimensional (0D) carbon forms (fullerenes and carbon dots) have encouraged researchers to explore them in the field of wastewater treatment through membrane technologies as they are biocompatible, which is the ultimate requirement to ensure the safety of drinking water. Thus, the purpose of this review is to highlight and summarize current advances in the field of water purification/treatment using 0D carbon-polymer-based nanocomposite membranes. Particular emphasis is placed on the development of 0D carbon forms embedded into a variety of polymer membranes and their influence on the improved performance of the resulting membranes. Current challenges and opportunities for future research are discussed.

Acid-sensing ion channels in trigeminal ganglion neurons innervating the orofacial region contribute to orofacial inflammatory pain.

Orofacial pain is a common clinical symptom that is accompanied by tooth pain, migraine and gingivitis. Accumulating evidence suggests that acid-sensing ion channels (ASICs), especially ASIC3, can profoundly affect the physiological properties of nociception in peripheral sensory neurons. The aim of this study is to examine the contribution of ASICs in trigeminal ganglion (TG) neurons to orofacial inflammatory pain. A Western blot (WB), immunofluorescence assay of labelled trigeminal ganglion neurons, orofacial formalin test, cell preparation and electrophysiological experiments are performed. This study demonstrated that ASIC1, ASIC2a and ASIC3 are highly expressed in TG neurons innervating the orofacial region of rats. The amplitude of ASIC currents in these neurons increased 119.72% (for ASIC1-like current) and 230.59% (for ASIC3-like current) in the formalin-induced orofacial inflammatory pain model. In addition, WB and immunofluorescence assay demonstrated a significantly augmented expression of ASICs in orofacial TG neurons during orofacial inflammation compared with the control group. The relative protein density of ASIC1, ASIC2a and ASIC3 also increased 58.82 ± 8.92%, 45.30 ± 11.42% and 55.32 ± 14.71%, respectively, compared with the control group. Furthermore, pharmacological blockade of ASICs and genetic deletion of ASIC1 attenuated the inflammation response. These findings indicate that peripheral inflammation can induce the upregulation of ASICs in TG neurons, causing orofacial inflammatory pain. Additionally, the specific inhibitor of ASICs may have a significant analgesic effect on orofacial inflammatory pain.

Priming the Surface of Orthopedic Implants for Osteoblast Attachment in Bone Tissue Engineering.

The development of better orthopedic implants is incessant. While current implants can function reliably in the human body for a long period of time, there are still a significant number of cases for which the implants can fail prematurely due to poor osseointegration of the implant with native bone. Increasingly, it is recognized that it is extremely important to facilitate the attachment of osteoblasts on the implant so that a proper foundation of extracellular matrix (ECM) can be laid down for the growth of new bone tissue. In order to facilitate the osseointegration of the implant, both the physical nanotopography and chemical functionalization of the implant surface have to be optimized. In this short review, however, we explore how simple chemistry procedures can be used to functionalize the surfaces of three major classes of orthopedic implants, i.e. ceramics, metals, and polymers, so that the attachment of osteoblasts on implants can be facilitated in order to promote implant osseointegration.

Polysulfone membranes coated with polymerized 3,4-dihydroxy-l-phenylalanine are a versatile and cost-effective synthetic substrate for defined long-term cultures of human pluripotent stem cells.

Clinical and industrial applications of human pluripotent stem cells (hPSC) require large amounts of cells that have been expanded under defined conditions. Labor-intensive techniques and ill-defined or expensive compounds and substrates are not applicable. Here we describe a chemically defined synthetic substrate consisting of polysulfone (PSF) membranes coated with polymerized 3,4-dihydroxy-l-phenylalanine (DOPA). DOPA/PSF is inexpensive and can be easily produced at various shapes and sizes. DOPA/PSF supports long-term self-renewal of undifferentiated human embryonic (hESC) and human induced pluripotent stem cells (hiPSC) under defined conditions. Pluripotency is maintained for at least 10 passages. Adhesion of hPSC to DOPA/PSF is mainly mediated by a specific integrin heterodimer. Proliferation and gene expression patterns on DOPA/PSF and control substrates are comparable. Labor-intensive cultivation methods and use of serum or coating with proteins are not required. Together, these features make DOPA/PSF attractive for applications where large-scale expansion of human pluripotent stem cells under defined conditions is essential.

Nonwoven-based gelatin/polycaprolactone membrane loaded with ERK inhibitor U0126 for treatment of tendon defects.

BACKGROUND: Tendon is a major component of musculoskeletal system connecting the muscles to the bone. Tendon injuries are very common orthopedics problems leading to impeded motion. Up to now, there still lacks effective treatments for tendon diseases. METHODS: Tendon stem/progenitor cells (TSPCs) were isolated from the patellar tendons of SD rats. The expression levels of genes were evaluated by quantitative RT-PCR. Immunohistochemistry staining was performed to confirm the presence of tendon markers in tendon tissues. Bioinformatics analysis of data acquired by RNA-seq was used to find out the differentially expressed genes. Rat patellar tendon injury model was used to evaluate the effect of U0126 on tendon injury healing. Biomechanical testing was applied to evaluate the mechanical properties of newly formed tendon tissues. RESULTS: In this study, we have shown that ERK inhibitor U0126 rather PD98059 could effectively increase the expression of tendon-related genes and promote the tenogenesis of TSPCs in vitro. To explore the underlying mechanisms, RNA sequencing was performed to identify the molecular difference between U0126-treated and control TSPCs. The result showed that GDF6 was significantly increased by U0126, which is an important factor of the TGFß superfamily regulating tendon development and tenogenesis. In addition, NBM (nonwoven-based gelatin/polycaprolactone membrane) which mimics the native microenvironment of the tendon tissue was used as an acellular scaffold to carry U0126. The results demonstrated that when NBM was used in combination with U0126, tendon healing was significantly promoted with better histological staining outcomes and mechanical properties. CONCLUSION: Taken together, we have found U0126 promoted tenogenesis in TSPCs through activating GDF6, and NBM loaded with U0126 significantly promoted tendon defect healing, which provides a new treatment for tendon injury.

rhBMP-2 not alendronate combined with HA-TCP biomaterial and distraction osteogenesis enhance bone formation.

INTRODUCTION: The long treatment duration of distraction osteogenesis (DO) usually causes some complications such as re-fracture, non-union. We have previously demonstrated that the combined use of biomaterial with distraction osteogenesis technique can enhance bone formation and consolidation. This study further tested whether the use of biological agents such as rhBMP-2 or alendronate together with biomaterials in DO will further promote bone formation. METHODS: A 1.0-cm tibial shaft was removed in the left tibia of 30 rabbits. The 1.0-cm defect gap was reduced to 0.5 cm and the remaining 0.5-cm defect gap was filled with 0.5-cm restorable hydroxyapatite/tri-calcium phosphates (HA/TCP) cylindrical block. The animals were divided into three groups with the following added on the HA/TCP block: Group A 50 µl of saline, Group B 75 µg rhBMP-2 in 50 µl of saline, Group C 250 µg alendronate in 50 µl saline. The tibia was then fixed with unilateral lengthener and lengthening started 7 days after at a rate of 1.0 mm/day for 5 days. All animals were terminated at day 37 following surgery. The excised bone specimens were subject to micro-CT, mechanical testing and histological examinations. RESULTS: Bone mineral density and content were significantly higher in Groups A and B compared to Group C and the mechanical properties of the regenerates in Group B were highest. Micro-CT and histological examinations also confirmed that the regenerates in Group B had the most advanced bone formation, consolidation and remodeling comparing to other groups. CONCLUSION: The combined use of rhBMP-2 with HA-TCP biomaterial in DO has significantly enhanced bone formation and consolidation than using the HA-TCP biomaterials alone, whereas the use of alendronate has inhibitory effects on bone formation.

Measurement of operative femoral anteversion during cementless total hip arthroplasty and influencing factors for using neck-adjustable femoral stem.

BACKGROUND: Placement of femoral stem in excessive anteversion or retroversion can cause reduced range of motion, prosthetic impingement, and dislocation. The aim of this study was to assess the operative femoral anteversion in patients treated with total hip arthroplasty (THA) and analyze the need of adjusting stem anteversion. METHODS: We retrospectively included 101 patients (126 hips) who underwent cementless THA with a manual goniometer to determine the femoral anteversion between October 2017 and December 2018. The operative femoral anteversion we measured was recorded during THA. We further divided those hips into three subgroups based on the range of operative femoral anteversion: group 1 (<10°), group 2 (10-30°), and group 3 (>30°) and compared the differences of their demographic data. Univariate and multivariate logistic regression were used to identify the influencing factors for the need of neck-adjustable femoral stem. The clinical and radiographic outcomes were also assessed. Perioperative complications were recorded. RESULTS: After THA, the Harris hip scores improved from 52.87 ± 15.30 preoperatively to 90.04 ± 3.31 at the last follow-up (p < 0.001). No implant loosening, stem subsidence, and radiolucent lines were observed on radiographs. No severe complications occurred and no components needed revision at the latest follow-up. The mean operative femoral anteversion was 14.21° ± 11.80° (range, -9 to 60°). Patients with femoral anteversion more than 30° were about 10 years younger than others. Femoral anteversion >30° was more common in patients with developmental dysplasia of the hip (DDH). There were totally 14 hips treated with the neck-adjustable femoral stem. From the univariate analysis, we can observe that female sex, diagnosis of DDH (compared with osteonecrosis), and higher operative femoral anteversion and its value >30° (compared with <10°) are associated with higher rates of using the neck-adjustable femoral stem. However, all these factors were no longer considered as independent influencing factors when mixed with other factors. CONCLUSIONS: This study highlighted the significance of operative femoral anteversion. Identification of abnormal femoral anteversion could assist in adjusting stem anteversion and reduce the risk of dislocation after THA.

Clinical effects of staged joint replacement in patients with septic arthritic knee.

OBJECTIVE: To assess the clinical effect of staged joint replacement for the treatment of septic arthritic knee and the therapeutic differences between antibiotic cement beads and the tibial plateau spacer. METHODS: Twenty-three patients (24 knee joints) treated with a staged joint replacement for septic arthritis knee were retrospectively reviewed between March 2014 and April 2018. At the first stage, thorough debridement and irrigation with self-made antibiotic cement beads or tibial plateau spacer were performed. After that, systemic antibiotic treatment was followed; when the infection was surely eliminated, the second-stage TKA was performed. Knee mobility (range of motion, abbreviated to ROM) and function (HSS scores system) were evaluated before surgery, in the interval period, and after joint replacement. RESULTS: All patients finished follow-up, and the mean follow-up time was 27.3 months (12-54 months). Each group has one patient replaced with a homotypic spacer, and all patients eventually cleared the infection. None of the patients had a recurrent infection. The mobility and HSS scores of the two groups were significantly improved postoperation (p < 0.05). And there was no significant difference in the post-surgery ROM (p = 0.153) and the HSS score (p = 0.054) between the two groups. CONCLUSION: Staged joint replacement is an efficacious way for septic arthritic knees, whether tibial plateau spacer or antibiotic cement beads were used, which can effectively control infection and improve knee function.

In Vivo Reconstruction of the Acetabular Bone Defect by the Individualized Three-Dimensional Printed Porous Augment in a Swine Model.

METHODS: As an acetabular bone defect model created in Bama miniswine, an augment individually fabricated by 3D print technique with Ti6Al4V powders was implanted to repair the defect. Nine swine were divided into three groups, including the immediate biomechanics group, 12-week biomechanics group, and 12-week histological group. The inner structural parameters of the 3D printed porous augment were measured by scanning electron microscopy (SEM), including porosity, pore size, and trabecular diameter. The matching degree between the postoperative augment and the designed augment was assessed by CT scanning and 3D reconstruction. In addition, biomechanical properties, such as stiffness, compressive strength, and the elastic modulus of the 3D printed porous augment, were measured by means of a mechanical testing machine. Moreover, bone ingrowth and implant osseointegration were histomorphometrically assessed. RESULTS: In terms of the inner structural parameters of the 3D printed porous augment, the porosity was 55.48 ± 0.61%, pore size 319.23 ± 25.05 µm, and trabecular diameter 240.10 ± 23.50 µm. Biomechanically, the stiffness was 21464.60 ± 1091.69 N/mm, compressive strength 231.10 ± 11.77 MPa, and elastic modulus 5.35 ± 0.23 GPa, respectively. Furthermore, the matching extent between the postoperative augment and the designed one was up to 91.40 ± 2.83%. Besides, the maximal shear strength of the 3D printed augment was 929.46 ± 295.99 N immediately after implantation, whereas the strength was 1521.93 ± 98.38 N 12 weeks after surgery (p = 0.0302). The bone mineral apposition rate (µm per day) 12 weeks post operation was 3.77 ± 0.93 µm/d. The percentage bone volume of new bone was 22.30 ± 4.51% 12 weeks after surgery. CONCLUSION: The 3D printed porous Ti6Al4V augment designed in this study was well biocompatible with bone tissue, possessed proper biomechanical features, and was anatomically well matched with the defect bone. Therefore, the 3D printed porous Ti6Al4V augment possesses great potential as an alternative for individualized treatment of severe acetabular bone defects.

The use of augmented antibiotic-loaded cement spacer in periprosthetic joint infection patients with acetabular bone defect.

BACKGROUND: Spacer complications may affect final clinical outcome of the two-stage approach in periprosthetic joint infection (PJI) patients. This study aimed to investigate clinical outcomes and complications of augmented antibiotic-loaded cement spacer in PJI patients with acetabular bone defect. METHODS: Data on PJI patients with acetabular bone defect receiving two-stage revision from January 2009 to December 2016, in our hospital were retrospectively reviewed. Screw-cement-shell was used to improve the stability of the hip with acetabular wall defect. Handmade acetabular spacer could prevent femoral spacer entering into pelvis in patients with acetabular internal wall defect. A total of 26 patients (11 males and 15 females) were included in the current study. Their mean age was 46.7 ± 15.4 years old. Clinical outcomes and complications were measured. RESULTS: Twenty-one of total 26 hips (21/26, 80.8%) showed positive cultures and 15/26 (57.7%) samples were cultured with staphylococcus. Of enrolled patients, 5/26 (19.2%) developed mixed infection. There was one patient (3.8%) with spacer dislocation and two (7.7%) with spacer fracture. One patient developed acute PJI 5 years after the second-stage revision, so overall success rate among these patients was 96.2%. Differences in Paprosky classifications before the first and second stage did not reach significant level (p > 0.05). Hip Harris score was raised from 40.9 ± 14.0 to 81.2 ± 11.2 (p < 0.05). CONCLUSIONS: Augmented antibiotic-loaded cement spacer could achieve satisfactory clinical outcomes in PJI patients with acetabular bone defect. It provided joint mobility, increased additional joint stability, and decreased iatrogenic bone defect caused by acetabular wear.

Cell culture on MEMS platforms: a review.

Microfabricated systems provide an excellent platform for the culture of cells, and are an extremely useful tool for the investigation of cellular responses to various stimuli. Advantages offered over traditional methods include cost-effectiveness, controllability, low volume, high resolution, and sensitivity. Both biocompatible and bio-incompatible materials have been developed for use in these applications. Biocompatible materials such as PMMA or PLGA can be used directly for cell culture. However, for bio-incompatible materials such as silicon or PDMS, additional steps need to be taken to render these materials more suitable for cell adhesion and maintenance. This review describes multiple surface modification strategies to improve the biocompatibility of MEMS materials. Basic concepts of cell-biomaterial interactions, such as protein adsorption and cell adhesion are covered. Finally, the applications of these MEMS materials in Tissue Engineering are presented.

Pyrolysis characteristics of organic components of municipal solid waste at high heating rates.

The pyrolysis characteristics of six representative organic components of municipal solid waste (MSW) and their mixtures were studied in a specially designed thermogravimetric analysis apparatus with a maximum recorded heating rate of 864.8 degrees Cmin(-1). The pyrolysis behavior of individual components was described by the Avrami-Erofeev equation. The influence of final temperature on individual components was studied, and it was concluded that final temperature was a factor in reaction speed and intensity, but that it played only a limited role in determining the reaction mechanism. The interactions between different components were evaluated, and it was concluded that the interaction between homogeneous materials was minimal, whereas the interaction between polyethylene and biomass was significant.

Reconstruction of Severe Acetabular Bone Defect with 3D Printed Ti6Al4V Augment: A Finite Element Study.

PURPOSE: The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment and TM augment and further to analyze the stress distribution and clinical safety of augments, screws, and bones. METHODS: The FEA model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment was established by the CT data of a patient with Paprosky IIIA defect. The von Mises stresses of augments, screws, and bones were analyzed by a single-legged stance loading applied in 3 increments (500 N, 2000 N, and 3000 N). RESULTS: The peak von Mises stresses under the maximal loading in the 3D printed augments, screws, and cortical bone were less than the yield strength of the corresponding component. However, the peak stress in the bone was greater than the yield strength of cancellous bone under walking or jogging loading. And under the same loading, the peak compressive and shear stresses in bone contact with TM augment were larger than these with 3D printed augment. CONCLUSIONS: The FEA results show that all the components will be intact under single-legged standing. However, partial cancellous bone contacted with 3D printed augment and screws will lose efficacy under walking or jogging load. So we recommend that patients can stand under full bearing, but can not walk or jog immediately after surgery.

Harnessing supramolecular peptide nanotechnology in biomedical applications.

The harnessing of peptides in biomedical applications is a recent hot topic. This arises mainly from the general biocompatibility of peptides, as well as from the ease of tunability of peptide structure to engineer desired properties. The ease of progression from laboratory testing to clinical trials is evident from the plethora of examples available. In this review, we compare and contrast how three distinct self-assembled peptide nanostructures possess different functions. We have 1) nanofibrils in biomaterials that can interact with cells, 2) nanoparticles that can traverse the bloodstream to deliver its payload and also be bioimaged, and 3) nanotubes that can serve as cross-membrane conduits and as a template for nanowire formation. Through this review, we aim to illustrate how various peptides, in their various self-assembled nanostructures, possess great promise in a wide range of biomedical applications and what more can be expected.

[COMPARISON OF HISTOACRYL TOPICAL SKIN ADHESIVE AND TRADITIONAL METHOD FOR WOUND CLOSURE IN TOTAL HIP ARTHROPLASTY].

OBJECTIVE: To compare the effectiveness between histoacryl topical skin adhesive and traditional method for wound closure in total hip arthroplasty (THA). METHODS: A total of 159 patients undergoing THA were divided into 2 groups between January and October in 2015. Subcuticular suture and histoacryl topical skin adhesive (cyanoacrylate adhesive) were used in 80 patients (100 hips) (test group), and traditional method (skin staples and wound drainage) was used in 79 patients (100 hips) (control group) for wound closure. There was no significant difference (P>0.05) in gender, age, body mass index, and etiology between 2 groups. The operation time, length of stay, incision pain visual analogue scale (VAS) score and healing of incision, and incision satisfaction evaluation, and classification were compared between 2 groups. RESULTS: All patients were followed up 3-6 months (mean. 4.7 months). There was no significant difference in operation time between 2 groups (Z=-0.527, P=0.598); but the length of stay of test group was less than that of control group (Z=-2.004, P=0.045). Incision exudation and dehiscence occurred in 1 case (1 hip) and 1 case (1 hip) of test group respectively; incision swollen, persistent wound exudation, exudation, and sutured drainage tube occurred in 2 cases (2 hips), 2 cases (2 hips), 4 cases (4 hips), and 1 case (1 hip) of control group. No statistically significant difference was found in VAS score between 2 groups at 15 days after operation (Z=-0.125, P=0.901), but wound healing score of test group was significantly higher than that of control group (Z=-2.943, P=0.003). Wound healing was class A in 98 hips and class B in 2 hips in test group, and was class A in 92 hips and class B in 8 hips in control group, and difference was statistically significant (χ2=3.789, P=0.048). The incision satisfaction of test group was significantly higher than that of control group (Z=-2.626, P=0.009). CONCLUSIONS: Compared with traditional method, histoacryl topical skin adhesive has decreased wound complication rate, and it is an easy and safe method with high satisfaction.

Towards a test to predict 5-fluorouracil toxicity: Pharmacokinetic data for thymine and two sequential metabolites following oral thymine administration to healthy adult males.

The fluoropyrimidine drugs 5-fluorouracil and its oral prodrug capecitabine remain first line therapy for solid tumours of the neck, breast and colon. However, significant and unpredictable toxicity affects about 10-25% of patients depending upon the mode of 5-fluorouracil delivery. The pharmacokinetics of thymine (5-methyluracil) may provide an approach for screening for 5-fluorouracil toxicity, based on the rationale that thymine is a close structural analogue of 5-fluorouracil and is catabolized by the same enzymatic pathway. Oral thymine loading tests were performed on 12 healthy volunteers. Each subject was given a single oral dose of 250mg thymine in capsule form. Blood, urine and saliva samples were collected pre-dose and up to 5h post-dose. Concentrations of thymine, and its catabolites dihydrothymine and ß-ureidoisobutyrate were analysed by HPLC-tandem mass spectrometry in plasma, urine and saliva. The pharmacokinetic data of healthy volunteers were analysed assuming a non-compartmental model. Thymine peaked quickly (30-45min) in plasma to a maximum concentration of 170±185µg/L (mean±SD). Clearance was high (mean 57.9L/h/kg) exceeding normal human liver blood flow, suggesting low systemic bioavailability; urinary recovery of the thymine dose was low (<1%). Apparent formation rate-limited kinetics were observed for dihydrothymine, and the plasma concentration of dihydrothymine was consistently 10-fold higher than that of thymine. Plasma ß-ureidoisobutyrate concentrations, on the other hand, were similar to that of thymine. Genotyping confirmed that pathological mutations of the DPYD gene were absent. The urinary excretion ratio of thymine/dihydrothymine was informative of the maximum concentration. Saliva thymine was highly variable. These data are potentially useful as a basis for developing of a screening procedure to prospectively identify patients who are at risk of toxicity from fluoropyrimidine drugs.

Calcium phosphate-chitosan composite scaffolds for bone tissue engineering.

Macroporous calcium phosphate-chitosan composite scaffolds were fabricated and evaluated for use in bone tissue engineering. Human osteoblast-like MG63 cells were cultured on the composite scaffolds, and their response to the materials was studied. Cell morphology, total protein content, and expression of classic markers for osteoblast differentiation were characterized. MG63 cells on the hydroxyapatite scaffolds nesting chitosan sponges (HC1) showed significantly higher alkaline phosphatase (ALP) level and osteocalcin (OC) production during the 11-day culture period, compared with the control culture on tissue culture plates. Cells on the chitosan scaffolds incorporated with hydroxyapatite powders (HC2) exhibited lower ALP activity during the 11-day culture period and OC secretion during the first 7 days, in comparison with that on HC1. The addition of calcium phosphate glass as in HC3 scaffolds increased the ALP and OC levels of MG63 cells. Our study indicated that the hydroxyapatite-matrix composite scaffolds might enhance the phenotype expression of MG63 cells, in comparison with chitosan-matrix scaffolds. Soluble calcium phosphate glasses should be added to the scaffolds to prevent chitosan from fast degradation that may affect the differentiation of osteoblast cells.

The use of a library of industrial materials to determine the nature of substrate-dependent performance of primary adherent human cells.

We developed a library of industrial materials, which can be applied to any adherent cell type for determining cell-material interactions. Bulk and surface chemistry as well as other material properties were characterized. The library covered broad ranges of various material properties. We applied the library to primary human endothelial and epithelial cells, which play important roles in tissue engineering and biomedical applications. The results revealed that substrate stiffness was the major determinant of cell performance. The ability to grow and differentiate on stiff or more compliant materials was cell type-dependent, but cell performance was consistently best on stiff and smooth materials. These results give new insights into the nature of substrate-dependent performance of primary human cells and are potentially useful for the development of improved biomaterials. The materials of the library can be easily accessed by the scientific community to determine cell-material interactions of any adherent cell type of interest.

Tendon-derived stem cells (TDSCs) promote tendon repair in a rat patellar tendon window defect model.

Injured tendons heal slowly and often result in the formation of mechanically and functionally inferior fibrotic scar tissue or fibrous adhesions. This study investigated the use of tendon-derived stem cells (TDSCs) for tendon repair in a rat patellar tendon window defect model. Fibrin glue constructs with or without GFP-TDSCs were transplanted into the window defect. The patellar tendons were harvested for histology, ex vivo fluorescent imaging and biomechanical test at various time points up to week 4. Our results showed that TDSCs significantly enhanced tendon healing as indicated by the increase in collagen production as shown by hematolxylin stain-ability of the tissue, improvement of cell alignment, collagen fiber alignment and collagen birefringence typical of tendon. The labeled cells were observed at weeks 1 and 2 and became almost undetectable at week 4. Both the ultimate stress and Young's modulus were significantly higher in the TDSCs group compared to those in the fibrin glue group at week 4. In conclusion, TDSCs promoted earlier and better repair in a rat patellar tendon window defect model.

The performance of primary human renal cells in hollow fiber bioreactors for bioartificial kidneys.

Bioartificial kidneys (BAKs) containing human primary renal proximal tubule cells (HPTCs) have been applied in clinical trials. The results were encouraging, but also showed that more research is required. Animal cells or cell lines are not suitable for clinical applications, but have been mainly used in studies on BAK development as large numbers of such cells could be easily obtained. It is difficult to predict HPTC performance based on data obtained with other cell types. To enable more extensive studies on HPTCs, we have developed a bioreactor containing single hollow fiber membranes that requires relatively small amounts of cells. Special hollow fiber membranes with the skin layer on the outer surface and consisting of polyethersulfone/polyvinylpyrrolidone were developed. The results suggested that such hollow fiber membranes were more suitable for the bioreactor unit of BAKs than membranes with an inner skin layer. An HPTC-compatible double coating was applied to the insides of the hollow fiber membranes, which sustained the formation of functional epithelia under bioreactor conditions. Nevertheless, the state of differentiation of the primary human cells remained a critical issue and should be further addressed. The bioreactor system described here will facilitate further studies on the relevant human cell type.