Tissue-engineered tendon nano-constructs for repair of chronic rotator cuff tears in large animal models.

Chronic rotator cuff tears (RCTs) are one of the most common injuries of shoulder pain. Despite the recent advances in surgical techniques and improved clinical outcomes of arthroscopically repaired rotator cuffs (RCs), complete functional recovery-without retear-of the RC tendon through tendon-to-bone interface (TBI) regeneration remains a key clinical goal to be achieved. Inspired by the highly organized nanostructured extracellular matrix in RC tendon tissue, we propose herein a tissue-engineered tendon nano-construct (TNC) for RC tendon regeneration. When compared with two currently used strategies (i.e., transosseous sutures and stem cell injections), our nano-construct facilitated more significant healing of all parts of the TBI (i.e., tendon, fibrocartilages, and bone) in both rabbit and pig RCT models owing to its enhancements in cell proliferation and differentiation, protein expression, and growth factor secretion. Overall, our findings demonstrate the high potential of this transplantable tendon nano-construct for clinical repair of chronic RCTs.

Plasma-assisted multiscale topographic scaffolds for soft and hard tissue regeneration.

The design of transplantable scaffolds for tissue regeneration requires gaining precise control of topographical properties. Here, we propose a methodology to fabricate hierarchical multiscale scaffolds with controlled hydrophilic and hydrophobic properties by employing capillary force lithography in combination with plasma modification. Using our method, we fabricated biodegradable biomaterial (i.e., polycaprolactone (PCL))-based nitrogen gas (N-FN) and oxygen gas plasma-assisted flexible multiscale nanotopographic (O-FMN) patches with natural extracellular matrix-like hierarchical structures along with flexible and controlled hydrophilic properties. In response to multiscale nanotopographic and chemically modified surface cues, the proliferation and osteogenic mineralization of cells were significantly promoted. Furthermore, the O-FMN patch enhanced regeneration of the mineralized fibrocartilage tissue of the tendon-bone interface and the calvarial bone tissue in vivo in rat models. Overall, the PCL-based O-FMN patches could accelerate soft- and hard-tissue regeneration. Thus, our proposed methodology was confirmed as an efficient approach for the design and manipulation of scaffolds having a multiscale topography with controlled hydrophilic property.

Tendon-Inspired Nanotopographic Scaffold for Tissue Regeneration in Rotator Cuff Injuries.

Acute and chronic rotator cuff (RC) tears are common etiologies of shoulder disabilities. Despite the advanced surgical techniques and graft materials available for tendon repair, the high re-tear rate remains a critical challenge in RC healing. Inspired by the highly organized nanotopography of the extracellular matrix (ECM) in tendon tissue of the shoulder, nanotopographic scaffolds are developed using polycaprolactone for the repair and regeneration of RC tendons. The scaffolds show appropriate flexibility and mechanical properties for application in tendon tissue regeneration. It is found that the highly aligned nanotopographic cues of scaffolds could sensitively control and improve the morphology, attachment, proliferation, and differentiation of tendon-derived cells as well as promote their wound healing capacity in vitro. In particular, this study showed that the scaffolds could promote tendon regeneration along the direction of the nanotopography in the rabbit models of acute and chronic RC tears. Nanotopographic scaffold-augmented rotator cuff repair showed a more appropriate healing pattern compared to the control groups in a rabbit RC tear model. We demonstrated that the tendon ECM-like nanoscale structural cues of the tendon-inspired patch may induce the more aligned tissue regeneration of the underlying tissues including tendon-to-bone interface.

How Long Should We Wait to Create the Goutallier Stage 2 Fatty Infiltrations in the Rabbit Shoulder for Repairable Rotator Cuff Tear Model?

BACKGROUND: Significant proportion of rotator cuff tears (RCTs) in clinical field are of a kind of repairable tear wherein the degree of fatty infiltration is of Goutallier stage 1 or stage 2. Therefore, the animal model, showing similar fatty infiltration, seems preferable for researches. The purpose of this study is to find out the proper time frame in which there is Goutallier stage 1 or stage 2 fatty infiltration in the rabbit RCT model for the research of repairable RCT in humans. METHODS: Supraspinatus tendon tears were created in forty male New Zealand white rabbits at their right shoulder (n= 8 for each group), and a sham operation on the left shoulder. Rabbits were divided into five groups (2nd, 4th, 6th, 8th, and 12th weeks). Specimens were harvested from the central portion of the supraspinatus muscle for haematoxylin and eosin (H &E) staining, followed by histological and Goutallier grading evaluation. Results are expressed as mean ± standard deviation by Sigma Plot software (version 7.0). RESULTS: At two weeks, mainly lipoblasts were observed around the muscle fibers, and at four weeks these lipoblasts were replaced by mature adipocytes with fatty infiltration amount (2.13 ± 0.35). The degree of muscle atrophy was (1.50 ± 0.53) at four weeks compared to sham group (0.88 ± 0.64) with significant difference (p < 0.05). The inflammatory process appeared as two phases. At two weeks, it was increased with grading value (1.88 ± 0.35). However, in the four-week group, it showed a sharp decrease (0.50 ± 0.53). At six weeks, inflammation reappeared to increase (1.13 ± 0.83). Then, a gradual decline appeared at eight weeks (0.88 ± 0.83) and at 12 weeks (0.50 ± 0.92). CONCLUSIONS: At two and four weeks, both fat distribution in rabbit supraspinatus muscles and Goutallier grading scale mostly appeared as grade 2. Therefore, we can consider four weeks to be a suitable period for making a repairable RCT animal model for the human research, considering the early acute tissue reaction at 2 weeks after the tendon tears.

Role of matrix metalloproteinase (MMP) 2 and MMP-9 in soft tissue sarcoma.

BACKGROUND: We investigated the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in malignant fibrous histiocytoma (MFH), and determined whether these could be useful as prognostic factors. METHODS: Among patients treated from 1993 to 2007, 30 cases of MFH were evaluated. Immunohistochemical staining was performed for MMP-2, MMP-9, TIMP-1, and TIMP-2 using paraffin wax-embedded blocks of MFH tissues. Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot and zymography were performed using fresh tissues obtained from 17 of the 30 cases. The levels of MMP and TIMP expression were compared between the MFH and normal control groups, and between non-metastatic and metastatic MFH groups. RESULTS: Expression levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 were higher in the MFH group than the control group by RT-PCR, Western blotting, and zymography. Immunohistochemical staining revealed that MMP-2 and MMP-9 protein expression was higher in the metastatic than in the non-metastatic group. The expression levels of MMP-2 and TIMP-1 were significantly higher in the metastatic than in the non-metastatic group (p < 0.05) by RT-PCR. By Western blot analysis, the expression levels of MMP-2, TIMP-1, and TIMP-2 were higher in the metastatic group (p < 0.05), but MMP-9 showed only a slight increase in the metastatic group compared with the non-metastatic group (p > 0.05). Finally, gelatin zymography analysis showed that the expression levels of the pro- and active forms of MMP-2 were significantly higher in the metastatic group (p < 0.05), but the expression of the pro- and active forms of MMP-9 showed a slight decrease in the metastatic group (p > 0.05). CONCLUSIONS: These results suggest that MMP-2, MMP-9, TIMP-1, and TIMP-2 may have important roles in the development and progression of MFH, and that the degree of expression of these metalloproteinases and their inhibitors, especially MMP-2, could be useful as prognostic factors related to metastasis in MFH.

Risedronate inhibits human osteosarcoma cell invasion.

BACKGROUND: Osteosarcoma is a highly malignant bone tumor and is the most commonly encountered malignant bone tumor in children and adolescents. Furthermore, significant numbers of patients eventually develop pulmonary metastases and succumb to the disease even after conventional multi-agent chemotherapy and surgical excision. Several solid tumors display enhanced expression of matrix metalloproteinases (MMPs), and recently clinical trials have been initiated on MMP-inhibitors. On the other hand, bisphosphonates (BPs), which have a profound effect on bone resorption, are widely used to treat osteoclast-mediated bone diseases. BPs are also known to inhibit tumor growths and metastases in some tumors such as breast cancer, renal cell carcinoma, and prostate cancer. METHODS: Two osteosarcoma cell lines (SaOS-2 and U2OS) were treated with risedronate (0, 0.1, 1, 10 microM) for 48 hours. Cell viabilities were determined using MTT assay, the mRNA levels of MMP-2 and MMP-9 were analyzed by reverse-transcription polymerase chain reaction, the amount of MMP-2 and MMP-9 protein were analyzed by Westernblot, the activities of MMP-2 and MMP-9 were observed by Gelatin zymography, and Matrigel invasion assays were used to investigate the invasive potential of osteosarcoma cell lines before and after risedronate treatment. RESULTS: The invasiveness of osteosarcoma cell lines (SaOS-2, U2OS) were reduced in a dose dependent manner follow 48 hour treatment of up to 10 microM of the risedronate at which concentration no cytotoxicity occurred. Furthermore, the gelatinolytic activities and protein and mRNA levels of MMP-2 and MMP-9 were also suppressed by increasing risedronate concentrations. CONCLUSION: Given that MMP-2 and MMP-9 are instrumental in tumor cell invasion, our results suggest the risedronate could reduce osteosarcoma cell invasion.

Expression and significance of TGF-beta isoform and VEGF in osteosarcoma.

This article demonstrates that the degree of VEG expression could be used as a clinically signific prognostic factor in osteosarcoma.