Cloning of STC-1 and analysis of its differential expression in Hezuo pig.

The purpose of this study was to examine STC-1's structure, function, and differential expression in large and miniature pigs. We cloned the Hezuo pig's coding sequence, compared its homology, and used bioinformatics to assess the structure. RT-qPCR and Western blot were used to detect the expression in ten tissues of Hezuo pig and Landrace pig. The results showed that Hezuo pig was most closely related to Capra hircus and most distantly related to Danio rerio. The protein STC-1 has a signal peptide and its secondary structure is dominated by the alpha helix. The mRNA expression in the spleen, duodenum, jejunum, and stomach of Hezuo pigs was higher than that of Landrace pigs. And except for heart and duodenum, expression of the protein in Hezuo pig was higher than in another. In conclusion, STC-1 is highly conserved among different breeds of pigs, and the expression and distribution of its mRNA and protein are different in large and miniature pigs. This work can lay the foundation for future study into the mechanism of action of STC-1 in Hezuo pigs and the enhancement of breeding in miniature pigs.

Dual-laser-actuated operation of small size objects at a liquid interface.

This work focuses on the use, for the first time to our knowledge, of dual laser beams in photothermal-effect-based propulsion of small size objects at liquid interfaces. Compared with the single-laser mode, dual-laser-actuated operation turns out to be much more controllable with high quality, efficiency, and anti-interference capacity, which can be achieved through automated programming instead of through manual operation. A series of experiments were carried out to verify the principle, with the effects of laser power, laser-spot distance, and movement speed discussed in detail. The findings of this work might provide some insights into the development of intelligent macro/micro-operation systems for manipulating objects at different scales, such as drug particles and cells at liquid interfaces in the future.

Basal Ganglionic Germinoma With Syncytiotrophoblastic Giant Cells Mimicking a Growing Hematoma.

Basal ganglionic germinoma (BGG) with syncytiotrophoblastic giant cells (STGC) is a rare type of ectopic germ cell tumors with mild elevation of human chorionic gonadotropin level. Intratumoral hemorrhage is not uncommon for BGG, but presenting with repeated hemorrhage is very rare. Herein, we described an extremely rare case of BGG with STGC mimicking a growing hematoma. Furthermore, the characteristics, treatment, and prognosis of BGG with STGC were investigated and reviewed.

Persistent mechanical stretch-induced calcium overload and MAPK signal activation contributed to SCF reduction in colonic smooth muscle in vivo and in vitro.

Gastrointestinal (GI) distention is a common pathological characteristic in most GI motility disorders (GMDs), however, their detail mechanism remains unknown. In this study, we focused on Ca2+ overload of smooth muscle, which is an early intracellular reaction to stretch, and its downstream MAPK signaling and also reduction of SCF in vivo and in vitro. We successfully established colonic dilation mouse model by keeping incomplete colon obstruction for 8 days. The results showed that persistent colonic dilation clearly induced Ca2+ overload and activated all the three MAPK family members including JNK, ERK and p38 in smooth muscle tissues. Similar results were obtained from dilated colon of patients with Hirschsprung's disease and stretched primary mouse colonic smooth muscle cells (SMCs). Furthermore, we demonstrated that persistent stretch-induced Ca2+ overload was originated from extracellular Ca2+ influx and endoplasmic reticulum (ER) Ca2+ release identified by treating with different Ca2+ channel blockers, and was responsible for the persistent activation of MAPK signaling and SCF reduction in colonic SMCs. Our results suggested that Ca2+ overload caused by smooth muscle stretch led to persistent activation of MAPK signaling which might contribute to the decrease of SCF and development of the GMDs.

Inhibition of miR-222-3p activity promoted osteogenic differentiation of hBMSCs by regulating Smad5-RUNX2 signal axis.

miRNAs are recently found playing important roles in osteogenesis. In this study, we identified that miR-222-3p decreased during osteogenic differentiation of human mesenchymal stem cells (hBMSCs) using Quantitative Real-Time Reverse Transcription PCR (qRT-PCR). Furthermore, we investigated the effect of miR-222-3p on osteogenic differentiation of hBMSCs. Inhibition of miR-222-3p function in hBMSCs using infection of lentiviruses carrying miR-222-3p specific inhibitor promoted expression of osteoblast-specific genes, alkaline phosphatase (ALP) activity, and matrix mineralization. Whereas, overexpression of miR-222-3p inhibited osteoblast differentiation of hBMSCs in vitro. Moreover, Smad5 and RUNX2, which are the critical transcription factors in osteogenic differentiation, were predicted to be targets of miR-222-3p by bioinformatic analysis. Overexpression of miR-222-3p in hBMSCs significantly suppressed the protein levels of Smad5 and RUNX2, while inhibition of miR-222-3p increased their protein levels. Furthermore, inhibition of miR-222-3p increased phosphorylation of Smad1/5/8, which regulated the expression of osteogenic genes. Our findings suggest that suppression of miR-222-3p activity promoted osteogenic differentiation hBMSCs through regulating Smad5-RUNX2 signaling axis.

Conditioned medium from human amniotic epithelial cells may induce the differentiation of human umbilical cord blood mesenchymal stem cells into dopaminergic neuron-like cells.

Dopaminergic (DA) neuron therapy has been established as a new clinical tool for treating Parkinson's disease (PD). Prior to cell transplantation, there are two primary issues that must be resolved: one is the appropriate seed cell origin, and the other is the efficient inducing technique. In the present study, human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) were used as the available seed cells, and conditioned medium from human amniotic epithelial cells (ACM) was used as the inducing reagent. Results showed that the proportion of DA neuron-like cells from hUCB-MSCs was significantly increased after cultured in ACM, suggested by the upregulation of DAT, TH, Nurr1, and Pitx3. To identify the process by which ACM induces DA neuron differentiation, we pretreated hUCB-MSCs with k252a, the Trk receptor inhibitor of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), and found that the proportion of DA neuron-like cells was significantly decreased compared with ACM-treated hUCB-MSCs, suggesting that NGF and BDNF in ACM were involved in the differentiation process. However, we could not rule out the involvement of other unidentified factors in the ACM, because ACM + k252a treatment does not fully block DA neuron-like cell differentiation compared with control. The transplantation of ACM-induced hUCB-MSCs could ameliorate behavioral deficits in PD rats, which may be associated with the survival of engrafted DA neuron-like cells. In conclusion, we propose that hUCB-MSCs are a good source of DA neuron-like cells and that ACM is a potential inducer to obtain DA neuron-like cells from hUCB-MSCs in vitro for an ethical and legal cell therapy for PD.

A possible gene silencing mechanism: hypermethylation of the Keap1 promoter abrogates binding of the transcription factor Sp1 in lung cancer cells.

Hypermethylation often leads to gene silencing; however, the mechanism responsible for the low expression resulting from hypermethylation of the tumor suppressor gene Kelch-like ECH-associating protein 1 (Keap1) in human lung cancer cell lines remains unclear. In this study, using promoter deletion and site mutagenesis assays, we determined that one transcription factor stimulating protein-1 (Sp1) regulatory element in the Keap1 promoter region was important for the transcription of Keap1 in A549 cells. We demonstrated that the transcription factor Sp1 can directly bind to this element in the normal bronchial epithelial BEAS-2B cell line but not in A549 cells, as assessed with chromatin immunoprecipitation (ChIP). EMSAs and supershift assays also showed that CpG island methylation could abrogate Sp1 binding to the Keap1 promoter. Moreover, Keap1 mRNA decreased by 50% after the knock-down of Sp1 with siRNA in BEAS-2B cells, whereas the over-expression of Sp1 led to a dramatic increase in Keap1 promoter activity. The treatment of A549 cells with 5-aza-2'-deoxycytidine restored the binding of Sp1 to the promoter and Keap1 expression. Our results indicate that Sp1 is essential for Keap1 expression and that promoter methylation blocks Sp1 binding in A549 cells. These results demonstrate that hypermethylation may act as an epigenetic gene silencing mechanism, i.e., the inhibition of Sp1 binding to the hypermethylated Keap1 promoter in lung cancer cells, which suggests new approaches to lung cancer treatment.

A Wide-Range Stiffness-Tunable Soft Actuator Inspired by Deep-Sea Glass Sponges.

Achieving both high compliance and stiffness is a key issue in stiffness-tunable soft robots. A wide-range variable-stiffness method keeping pure soft characteristic is proposed by bioinspired design of deep-sea glass sponges adopting thermoplastic starch. The stiffness-tunable mechanism is designed through force analysis and optimization of its bionic cellular structure. It is fabricated with load-weight ratio exceeding 470. Then, a wide-range stiffness-tunable omnidirectional-bending soft actuator (WOSA) is realized, and the bending stiffness model is established. Comparative experiments of stiffness and deformation are conducted on WOSA and a pure soft actuator (PSA) with the same size. Results show that the WOSA can get 92.3 times initial bending and 70.8 times torsional stiffness variation range, of which the flexibility is even better than PSA. A gripper assembled by three WOSAs is verified through stiffness adjustment that it can grasp different weight fragile, soft items from the unshelled fresh egg, boiled egg yolk to grapes. It can even lift a dumbbell weighting 3.32 kg. Finally, a manipulator demonstrated its potential in future minimally invasive surgical applications due to its wide stiffness range and large deformation capacity.

A Human-Inspired Soft Finger with Dual-Mode Morphing Enabled by Variable Stiffness Mechanism.

Elevating stiffness without compromising compliance and agility is a key problem for soft finger applications, especially for articulate ones. Inspired by human finger, a multijoint soft finger with dual morphing through active/passive variable rigidity is proposed. The fabricated soft finger weighs 27.4 g. Conductive thermoplastic starch polymers (CTPSs) are embedded in a U-shape-joint pneumatic soft actuator segmentally like biological phalanges. Their stiffness can be independently adjusted utilizing customized thermomechanical property. Yoshimura origami imitating ligaments can passively match deformation and stiffness of the joints. Through electrothemal activation of CTPSs, the finger can realize dual independent articulate morphing: stiffened phalanges (mode 1) for dexterous manipulation and heavy load, softened phalanges (mode 2) for large deformation contact and light load. Comparative experiments of bending angle, output force, and stiffness are carried out between the active and passive stiffness adjustment of mode 1 and mode 2. The results show that the output force and stiffness of the finger adopting mode 1 can be improved more than two times and five times, and its compliance using mode 2 is almost similar, compared with the pure soft one. To further demonstrate performances of dual-mode morphing, a three-fingered gripper is assembled for grasping and manipulating targets with different shapes, sizes, rigidity, and weight, including playing card, unshelled raw egg, grapes, and unscrewing the bottle cap. It can successfully lift a dumbbell weighing 1460 g with a 7.6 load/weight ratio through a two-mode switch.

A Gas-Ribbon-Hybrid Actuated Soft Finger with Active Variable Stiffness.

A new hybrid actuated soft finger with active variable stiffness is proposed for the first time by integrating gas-driven and ribbon-driven mechanisms. By carefully coordinating the two mechanisms, the bending deformation and the stiffness modulation processes of the soft finger can be uncoupled, providing it with both high flexibility and good variable stiffness. Although the soft finger, made entirely from flexible materials, works under a low and safe gas pressure of below 35 kPa, the maximum bending angle reaches ∼210°, and a single soft finger can withstand a weight of 1.25 kg. For any bending angle, with the help of the ribbon-driven mechanism, the stiffness of the soft finger can increase by three to six times. In addition, theoretical models are established for the evaluation of the bending-deformation characteristic and the output force of the soft finger, which are verified by experiments. A dual-finger soft robotic gripper is assembled by utilizing two soft fingers, which can easily and stably grab various objects with different sizes, shapes, and weights. Both the theoretical and experimental results indicate that the proposed gas-ribbon-hybrid actuated mechanism can effectively enhance the variable stiffness property of a soft finger while retaining its good compliance with the surroundings. This work might provide future insights for the development of compact and cost-effective soft end effectors with active variable stiffness.

LINC01224 accelerates malignant transformation via MiR-193a-5p/CDK8 axis in gastric cancer.

BACKGROUND: Gastric cancer (GC) is a malignant tumor with a significantly high mortality rate, yet, its pathogenesis is not fully understood. Bioinformatics predicted that LINC01224 is highly expressed in stomach adenocarcinoma (STAD), and showed that LINC01224 adsorbed miR-193a-5p to target CDK8. Therefore, this study intended to verify the effect of the LINC01224/miR-193a-5p/CDK8 axis on the biological behavior of gastric cancer. METHODS: Expressions of LINC01224, miR-193a-5p, CDK8, apoptosis-, and EMT-related genes were analyzed using the GEPIA website, RT-qPCR, in situ hybridization, and Western blot as needed. Bioinformatics and dual luciferase assay were used to evaluate the relationship between LINC01224, miR-193a-5p, and CDK8. Functional experiments and rescue experiments (MTT assay, flow cytometry, wound healing assay, and Transwell) were conducted to detect the effects of the above genes on the biological characteristics of GC cells. Tumorigenesis assay was used to verify the results of in vitro experiments. RESULTS: LINC01224 adsorbed miR-193a-5p to target and upregulate CDK8. The expressions of LINC01224 and CDK8 were increased, while the expression of miR-193a-5p was decreased in GC. Overexpressed LINC01224 promoted cell viability, migration and invasion, accelerated tumor formation, attenuated apoptosis, inhibited the expressions of apoptosis-related proteins, and promoted the expressions of EMT-related proteins, whereas silenced LINC01224 led to the opposite effect. MiR-193a-5p inhibitor partially offset the effect of silenced LINC01224; interestingly, siCDK8 significantly reversed the effect of miR-193a-5p inhibitor on GC cells. CONCLUSION: LINC01224 affects the biological behavior of gastric cancer by mediating miR-193a-5p to regulate CDK8.

Effects of extremely low-frequency magnetic field on growth and differentiation of human mesenchymal stem cells.

Human Mesenchymal Stem Cells (hMSCs) were exposed to a developed extremely low-frequency (ELF) magnetic fields (50 Hz ,20 mT ELF) system to evaluate whether exposure to (ELF) magnetic fields affects growth, metabolism, and differentiation of hMSCs. MTT method was used to determine the growth and metabolism of hMSCs following exposure to ELF magnetic fields. Na(+)/K(+) concentration and osmolality of extracellular were measured after exposured culture. Alkaline phosphatase (ALP) assay and Calcium assay, ALP staining, and Alizarin red staining were performed to evaluate the osteogenic differentiation of hMSCs under the ELF magnetic field exposure. In these experiments, the cells were exposed to ELF for up to 23 days. The results showed that exposure to ELF magnetic field could inhibit the growth and metabolism of hMSC, but have no significant effect on differentiation of hMSCs. These results suggested that ELF magnetic field may influence the early development of hMSCs related adult cells.

The effect of neo-adjuvant chemotherapy on the improvement of oral cancer patients and the predictive value of miR-182 on its efficacy.

PURPOSE: This study aimed to observe the effect of neo-adjuvant chemotherapy on the improvement of oral cancer patients and investigate the predictive value of miR-182 on its efficacy. METHODS: A total of 143 patients with advanced oral cancer admitted to Yidu Central Hospital of Weifang from September 2015 to July 2017 formed the study group. Among them, there were 62 cases in the control group (surgery+postoperative radiotherapy) and 81 cases in the study group (preoperative neo-adjuvant chemotherapy+surgery+postoperative radiotherapy). The treatment effect and adverse reactions of patients were compared between the two groups. RT-PCR was used to detect the expression levels of serum miR-182 of patients before and after treatment. The 1-year survival of patients in the two groups was recorded and compared by follow-up. RESULTS: The total effective rate of patients in the study group was significantly higher than that of patients in the control group (p<0.05). The incidence of adverse reactions of patients in the study group was significantly higher than in the control group (p<0.05). There was no significant difference in the prognostic 1-year survival rate between the two groups. After treatment, the expression of miR-182 was lower than before treatment and in the study group it was significantly lower than the control group (p<0.05). ROC curve analysis showed that the area under the curve of miR-182 in the predictive value of oral cancer was 0.756. When the cut-off value was less than 1.823, the optimal specificity was 70.18% and the sensitivity was 75.86%. CONCLUSION: Neo-adjuvant chemotherapy can significantly improve the therapeutic effect, but the incidence of adverse reactions increases. miR-182 may be involved in the occurrence and deterioration of oral cancer and is a good indicator for predicting the treatment efficacy of patients with oral cancer.

miR-199b-5p promoted chondrogenic differentiation of C3H10T1/2 cells by regulating JAG1.

Mesenchymal stem cells (MSCs) are considered a promising candidate for use in cell-based therapy for cartilage repair. To promote understanding of the molecular control of chondrogenesis differentiation in MSCs, we compared the changes in microRNAs during in vitro chondrogenesis process of human bone-marrow mesenchymal stem cells (hBMSCs). MiR-199b-5p was up-regulated significantly during this process. The aim of the study was to investigate the effects of miR-199b-5p on chondrogenic differentiation of C3H10T1/2 MSC cells and explore the underlying mechanisms. MiR-199b-5p mimics or inhibitor were transfected into C3H10T1/2 cells, respectively, and then, the effects of miR-199b-5p on chondrogenic differentiation of C3H10T1/2 cells were detected. The results indicated that miR-199b-5p overexpression inhibited the growth of C3H10T1/2 cells but promoted transforming growth factor-ß3 (TGF-ß3)-induced C3H10T1/2 cells of chondrogenic differentiation, as supported by enhancing the gene and protein expression of chondrocyte specific markers of SOX9, aggrecan, and collagen type II (Col2a1). In contrast, inhibiting miR-199b-5p notably promoted the proliferation of C3H10T1/2 cells but decreased chondrogenic differentiation. Furthermore, mechanism studies revealed that JAG1 was a direct target of miR-199b-5p by dual luciferase reporter assays. While silencing of JAG1 by isRNA resulted an increase of chondrogenic differentiation. Further, JAG1 knockdown was demonstrated to block the effect of miR-199b-5p inhibition. In conclusion, the present study revealed for the first time that miR-199b-5p was the positive regulators to modulate chondrogenic differentiation of C3H10T1/2 cells by targeting JAG1. These findings may provide a novel insight on miRNA-mediated MSC therapy for cartilage related disorders.

A New Spiral-Type Inflatable Pure Torsional Soft Actuator.

Soft robot has become a hot topic recently due to its distinct advantages over traditional rigid robots such as high deformability and good impact resistance. However, the coupled deflections of flexile materials bring challenges to soft robotic research in many aspects such as kinematic modeling, dynamic analysis, and control. Besides, unwanted deformations might enlarge external dimensions of soft robots, causing a reduction in the efficiency and bringing about unexpected or harmful contacts with surrounding environments that will significantly affect the robots' performance. In this study, we propose a new inflatable soft actuator driven by two spiral chambers twined with fibers for the first time. A key feature of this actuator is that it possesses a pure and high-efficient torsional motion with no bending and extension movements when works without load, which reduces the difficulties of theoretical analysis and control to some extent. Kinematic model is established by combining virtual work principle and elastic strain energy function for nonlinear flexible materials. The new soft torsional actuator module is carefully designed and fabricated, of which both the kinematic property and output torque are investigated experimentally. Results show that the module exhibits good linearity with air pressure ranging from 35 to 100 kPa, and can provide a torsion angle of up to 110° with an angular displacement accuracy of ±2° in empty loaded conditions; the maximum output torque reaches 0.026 N·m with the corresponding air pressure of 100 kPa. Finally, three soft robots are assembled by utilizing this new, inflatable, pure, soft torsional actuator, and successfully carry out different manipulating tasks. This work might provide some insights into the design of linear soft actuators without coupled deformations in future.

Elevated SLC26A4 gene promoter methylation is associated with the risk of presbycusis in men.

Presbycusis affects approximately one-third of people over the age of 65 and is a worldwide health problem. In the current study, whether the methylation level of solute carrier family 26 member 4 (SLC26A4) predicted an increased risk of presbycusis was investigated. Peripheral blood samples from 102 patients with presbycusis and 104 controls were collected, and the methylation of the CpG sites of SLC26A4 was measured by applying pyrosequencing technology combined with sodium bisulfate DNA conversion chemistry. Within the SLC26A4 promoter region, one CpG site (CpG3) exhibited a significantly (P<0.0001) greater methylation level in the patients with presbycusis (26.5±5.56%) compared with the controls (23.8±3.85%). Significantly different CpG3 methylation levels were observed between the patients with presbycusis and the controls among the male participants (P=0.0004). In addition, a significant decrease in the transcriptional level of SLC26A4 in peripheral blood was observed in the patients with presbycusis compared with the controls. Furthermore, analyses of the receiver operating characteristic (ROC) curves indicated that CpG3 methylation at the SLC26A4 promoter predicted the risk of presbycusis in the male participants (AUC=0.684, 95% CI=0.584­0.784, P=0.001). The results demonstrated the significance of the CpG site methylation level of SLC26A4, and thus provides a potential marker for the diagnosis of presbycusis.

A water-walking robot mimicking the jumping abilities of water striders.

The highly efficient and agile water-surface locomotion of water striders has attracted substantial research attention. Compared with imitating the horizontal rowing motion, imitating the jumping capability of water striders is much more challenging because the strong interaction in the jumping process easily causes the robot to sink. This study focuses on designing a miniature robot capable of continuously jumping on the water surface. A spring-based actuating mechanism is proposed to produce a large jumping force. The center of gravity of the robot is carefully designed to allow the robot to jump on the surface continuously and smoothly. The influences of several critical factors, including the area of the supporting legs, the spring stiffness, the jumping angle, etc on jumping ability are analyzed by means of dynamic simulation and experiments. The jumping performance under different jumping angles is tested. The fabricated robot weighs approximately 10.2 g and can continuously jump on water with a maximum leap height and length of 120 and 410 mm, respectively. This study helps researchers understand the jumping mechanism of water striders and provides a reference for developing water-jumping robots that can perform various aquatic tasks in the future.

Design of a high-bandwidth tripod scanner for high speed atomic force microscopy.

Tip-scanning high-speed atomic force microscopes (HS-AFMs) have several advantages over their sample-scanning counterparts. Firstly, they can be used on samples of almost arbitrary size since the high imaging bandwidth of the system is immune to the added mass of the sample and its holder. Depending on their layouts, they also enable the use of several tip-scanning HS-AFMs in combination. However, the need for tracking the cantilever with the readout laser makes designing tip-scanning HS-AFMs difficult. This often results in a reduced resonance frequency of the HS-AFM scanner, or a complex and large set of precision flexures. Here, we present a compact, simple HS-AFM designed for integrating the self-sensing cantilever into the tip-scanning configuration, so that the difficulty of tracking small cantilever by laser beam is avoided. The position of cantilever is placed to the end of whole structure, hence making the optical viewing of the cantilever possible. As the core component of proposed system, a high bandwidth tripod scanner is designed, with a scan size of 5.8 µm × 5.8 µm and a vertical travel range of 5.9 µm. The hysteresis of the piezoactuators in X- and Y-axes are linearized using input shaping technique. To reduce in-plane crosstalk and vibration-related dynamics, we implement both filters and compensators on a field programmable analog array. Based on these, images with 512 × 256 pixels are successfully obtained at scan rates up to 1024 lines/s, corresponding to a 4 mm/stip velocity. SCANNING 38:889-900, 2016. © 2016 Wiley Periodicals, Inc.

C-kit signaling promotes proliferation and invasion of colorectal mucinous adenocarcinoma in a murine model.

It was reported that the receptor tyrosine kinase (RTK) family often highly expressed in several mucinous carcinomas. In the present study, we established a murine model of colorectal mucinous adenocardinoma (CRMAC) by treating C57 mice [both wild type (WT) and loss-of-function c-kit mutant type (Wads-/-)] with AOM+DSS for 37 weeks and found that c-kit, a member of RTK family, clearly enhanced the tumor cell proliferation by decreasing p53 and increasing cyclin D1 through AKT pathway. Significantly, c-kit strongly promoted tumor cell invasiveness by increasing ETV4, which induced MMP7 expression and epithelial-mesenchymal transition (EMT) via ERK pathway. In vitro up- or down-regulating c-kit activation in human colorectal cancer HCT-116 cells further consolidated these results. In conclusion, our data suggested that the c-kit signaling obviously promoted proliferation and invasion of CRMAC. Therefore, targeting the c-kit signaling and its downstream molecules might provide the potential strategies for treatment of patients suffering from CRMAC in the future.

Effects of releasing recombinant human growth and differentiation factor-5 from poly(lactic-co-glycolic acid) microspheres for repair of the rat degenerated intervertebral disc.

PURPOSE: The objective of this study was to investigate the therapeutic potential of poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with recombinant human growth and differentiation factor-5 (rhGDF-5) on the disc degeneration induced by needle puncture in a rat caudal disc model. METHODS: The rhGDF-5-loaded PLGA microspheres were prepared by the water-oil-water double-emulsion solvent evaporation method, and release kinetics was determined over 42 days. Rats that underwent 21-G needle puncture at rat tail discs were injected with rhGDF-5/PLGA microspheres at four weeks after needle injury. At eight weeks after the injection, disc height, glycosaminoglycans content, and DNA content of the discs were evaluated. In addition, gene expression analysis of aggrecan, collagen type I, and collagen type II in the rat nucleus pulposus was measured by real-time polymerase chain reaction. Rat discs were also assessed by histology using hematoxylin and eosin stain. RESULTS: Encapsulation of rhGDF-5 in PLGA microspheres guaranteed a sustained release of active rhGDF-5 for more than 42 days. The injection of GDF-5/PLGA microspheres resulted in a statistically significant restoration of disc height (p < 0.01), improvement of sulfated glycosaminoglycan (p < 0.05), DNA content (p < 0.05), and significantly increased mRNA levels of collagen type II (p < 0.01), and the differentiation index (the ratio of collagen type II to collagen type I, p < 0.01). In addition, rhGDF-5/PLGA microspheres treatment also improved histological changes induced by needle puncture. CONCLUSIONS: The results of this study suggest that injection of rhGDF-5 loaded in PLGA microspheres into rat tail discs may be as a promising therapy strategy to regenerate or repair the degenerative disc.