Regulatory roles of miRNAs 16, 133a, and 223 on osteoclastic bone destruction caused by breast cancer metastasis.

Osteolytic bone metastasis leads to skeletal­related events, resulting in a decline in the patient activities and survival; therefore, it is important to understand the mechanism underlying bone metastasis. Recent studies have suggested that microRNAs (miRNAs or miRs) are involved in osteoclast differentiation and/or osteolytic bone metastasis; however, the roles of miRNAs have not been elucidated. In the present study, the roles of miRNAs in bone destruction caused by breast cancer metastasis were investigated in vitro and in vivo. miR­16, miR­133a and miR­223 were transfected into a human breast cancer cell line, MDA­MB­231. The expression of osteolytic factors in conditioned medium (miR­CM) collected from the culture of transfected cells was assessed. To evaluate the effects of miRNAs on osteoclast differentiation and activities, tartrate­resistant acid phosphatase (TRAP) staining and bone resorptive assays were performed in osteoclasts following miR­CM treatment. To create in vivo bone metastasis models for histological and morphometric evaluation, miRNA­transfected MDA­MB­231 cells were transplanted into the proximal tibia of nude mice. Expression of osteolytic factors, including receptor activator for nuclear factor­κB ligand (RANKL), interleukin (IL)­1ß, IL­6, parathyroid hormone­related protein (PTHrP), and tumor necrosis factor (TNF), was increased in miR­16­CM, whereas it was decreased in both miR­133a­CM and miR­223­CM. TRAP staining and bone resorptive assays revealed that osteoclast function and activities were promoted by miR­16­CM treatment, whereas they were suppressed by miR­133a­CM and miR­223­CM. Consistent with in vitro findings, in vivo experiments revealed that the overexpression of miR­16 increased osteoclast activities and bone destruction in MDA­MB­231 cells, whereas the opposite results were observed in both miR­133a­ and miR­223­transfected MDA­MB­231 cells. Our results indicated that miR­16 promoted osteoclast activities and bone destruction caused by breast cancer metastasis in the bone microenvironment, whereas miR­133a and miR­223 suppressed them. These miRNAs could be potential biomarkers and therapeutic targets for breast cancer bone metastasis.

Surgical outcomes of metastatic bone tumors in the extremities (Surgical outcomes of bone metastases).

BACKGROUND: Skeletal related events due to metastatic bone tumors markedly affect the activities of daily living (ADL) and quality of life (QOL) in cancer patients. We focused on multidisciplinary therapy for metastatic bone tumors. This study aimed to evaluate the outcomes of surgical treatment for metastatic bone tumors in the extremities. METHODS: We retrospectively reviewed 114 patients who underwent surgical treatment for metastatic bone tumors of the extremities between 2008 and 2019 and 69 patients were reassessed for more than 6 months after surgery. The most common primary tumor was renal, followed by lung, thyroid, and breast cancers. We assessed 69 patients' performance status (PS), Barthel Index (BI) for ADL, EuroQol 5 Dimensions (EQ-5D) for QOL, and numerical rating scale (NRS) for pain and analyzed these postoperative values relative to preoperative values using Friedman's test. The postoperative overall survival and the prognostic factors were evaluated using the Kaplan-Meier method, the log-rank test and Cox proportional hazards analysis. RESULTS: The 1-year overall survival rate was 59%, and the median survival time after surgery was 20 months. Primary tumor, visceral metastasis, and surgical procedure were risk factors correlated with overall survival. PS, BI, EQ-5D, and NRS improved at 3 months after surgery and these improvements were maintained for 6 months after surgery regardless of the surgical procedure. CONCLUSIONS: The significant factors affecting survival after surgical treatment for bone metastases included the primary tumor, presence of visceral metastases, and internal fixation without tumor resection or curettage. Surgical treatment for metastatic bone tumors effectively reduced pain and improved PS, ADL, and QOL postoperatively after 3 months.

BNCT for primary synovial sarcoma.

Synovial sarcoma is a rare tumor requiring new treatment methods. A 46-year-old woman with primary monophasic synovial sarcoma in the left thigh involving the sciatic nerve, declining surgery because of potential dysfunction of the affected limbs, received two courses of BNCT. The tumor thus reduced was completely resected with no subsequent recurrence. The patient is now able to walk unassisted, and no local recurrence has been observed, demonstrating the applicability of BNCT as adjuvant therapy for synovial sarcoma. Further study and analysis with more experience accumulation are needed to confirm the real impact of BNCT efficacy for its application to synovial sarcoma.

Clinical Outcome of the Patients With Brain Metastasis from Soft Tissue Sarcomas.

BACKGROUND/AIM: This study aimed to evaluate the association of clinical characteristics with treatment outcomes to ascertain the appropriate treatment options for soft tissue sarcomas (STS) patients with brain metastasis (BM). PATIENTS AND METHODS: Medical records of STS patients with BM who were treated in our institutions were retrospectively reviewed, and analyzed to identify the factors associated with post-BM survival. RESULTS: Among the 509 STS patients, BM occurred in five patients (0.98%). The median survival after BM was 1.5 months. Histological subtypes of the primary lesions in the five BM patients were: two synovial sarcomas, one myxoid liposarcoma, one alveolar soft part sarcoma, and one rhabdomyosarcoma. Among the five BM patients, the post-BM survival of two patients, who underwent surgery and postoperative radiotherapy, was longer than that of the other patients (p<0.01). CONCLUSION: Combined surgery and postoperative radiotherapy effectively managed symptoms and prolonged survival in STS patients with BM.

A Cell-free Biodegradable Synthetic Artificial Ligament for the Reconstruction of Anterior Cruciate Ligament in a Rat Model.

Traditional Anterior Cruciate Ligament (ACL) reconstruction is commonly performed using an allograft or autograft and possesses limitations such as donor site morbidity, decreased range of motion, and potential infection. However, a biodegradable synthetic graft could greatly assist in the prevention of such restrictions after ACL reconstruction. In this study, artificial grafts were generated using "wet" and "dry" electrospinning processes with a biodegradable elastomer, poly (ester urethane) urea (PEUU), and were evaluated in vitro and in vivo in a rat model. Four groups were established: (1) Wet PEUU artificial ligament, (2) Dry PEUU artificial ligament, (3) Dry polycaprolactone artificial ligament (PCL), and (4) autologous flexor digitorum longus tendon graft. Eight weeks after surgery, the in vivo tensile strength of wet PEUU ligaments had significantly increased compared to the other synthetic ligaments. These results aligned with increased infiltration of host cells and decreased inflammation within the wet PEUU grafts. In contrast, very little cellular infiltration was observed in PCL and dry PEUU grafts. Micro-computed tomography analysis performed at 4 and 8 weeks postoperatively revealed significantly smaller bone tunnels in the tendon autograft and wet PEUU groups. The Wet PEUU grafts served as an adequate functioning material and allowed for the creation of tissues that closely resembled the ACL.

Chondrolipoma of the finger in a child: A case study.

Chondrolipoma is, based on the limited case reports available, an extremely rare histological variant of lipoma with the proliferation of mature adipocytes containing an area of true hyaline cartilage. Chondrolipoma is characterized by adult onset and is often identified in the breast, pharynx and tongue. The current study presents a case of chondrolipoma of the finger in an 11 year-old girl. Physical examination indicated a well-defined elastic soft mass, measuring 2.5x2 cm, on the dorsal aspect of the proximal phalanx of the left middle finger. Magnetic resonance imaging (MRI) revealed a well-circumscribed lesion with heterogeneous signal intensity. On T1- and T2-weighted images, the lesion indicated a predominantly marked hyperintense signal containing linear hypointense regions, and on fat-suppressed short-tau inversion recovery sequences, the lesion indicated a predominant hypointensity, with linear regions displaying hyperintensity. Marginal excision of the tumor was performed. Histologically, the major component of the tumor was mature adipose tissue containing a limited area of mature hyaline cartilage matrix, without lipoblasts or malignancy. The postoperative course of the patient was excellent, with no local recurrence three years after surgery. To the best of our knowledge, the current study outlines the first pediatric case of chondrolipoma arising in the finger.

Acquisition of cancer stem cell properties in osteosarcoma cells by defined factors.

BACKGROUND: Cancer stem cells (CSCs) are considered to be responsible for tumor initiation, formation, and poor prognosis of cancer patients. However, the rarity of CSCs in clinical samples makes it difficult to elucidate characteristics of CSCs, especially in osteosarcoma (OS). The aim of this study is to verify whether it is possible to generate CSC-like cells by transducing defined factors into an OS cell line. METHODS: We retrovirally transduced the Octamer-binding transcription factor 3/4 (OCT3/4), Kruppel-like factor 4 (KLF4), and SRY-box transcription factor 2 (SOX2) genes into the MG-63 human OS cell line (MG-OKS). Parental and GFP-transduced MG-63 cells were used as negative control. We assessed the properties of the generated cells in vitro and in vivo. Multiple comparisons among groups were made using a one-way analysis of variance (ANOVA) followed by post hoc testing with Tukey's procedure. RESULTS: MG-OKS cells in vitro exhibited the significantly increased mRNA expression levels of CSC markers (CD24, CD26, and CD133), decreased cell growth, increased chemoresistance and cell migration, and enhanced sphere formation. Notably, MG-OKS cells cultured under osteogenic differentiation conditions showed strongly positive staining for both Alizarin Red S and alkaline phosphatase, indicating osteogenesis of the cells. Gene ontology analysis of microarray data revealed significant upregulation of epidermal-related genes. Tumors derived from MG-OKS cells in vivo were significantly larger than those from other cells in µCT analysis, and immunohistochemical staining showed that Ki-67, osteocalcin, and HIF-1α-positive cells were more frequently detected in the MG-OKS-derived tumors. CONCLUSIONS: In this study, we successfully generated OS CSC-like cells with significantly enhanced CSC properties following transduction of defined factors.

Boron neutron capture therapy for clear cell sarcoma.

Clear cell sarcoma of tendons and aponeuroses (CCS) is a rare, malignant tumor arising in lower extremities with no effective treatment other than wide surgical resection. Here described is a case of primary CCS in the peroneal tendon of the right foot of a 54-year-old woman enrolled to undergo BNCT. The tumor mass post-BNCT disappeared totally without damage to other normal tissue, demonstrating, for the first time, the potential efficacy of BNCT in complete local control of CCS.

Extraskeletal Para-articular Osteochondroma of the Ankle Joint in a Child: A Case Report.

CASE: We present a rare case of extraskeletal para-articular osteochondroma (ESPAOC) in the ankle of a 9-year-old boy, which was causing pain and limiting the range of motion of the ankle joint. The lesion might have also contributed to the deformity of the medial aspect of the talus. Total resection resolved all of the symptoms, with no recurrence at 1-year postoperatively. CONCLUSION: Operative excision should be considered when ESPAOC directly restricts ankle motion because it can lead to chronic pain and joint degeneration if left untreated.

Soft tissue tumor with novel NR1D1-MAML1 fusion in a pediatric case.

We herein describe soft tissue tumor arising in the lower extremity of a pediatric patient. The tumor displayed a unique and wide range of histological features, sheet-like and cohesive growth pattern consisting of enlarged round to epithelioid atypical cells with a large alveolar and pseudopapillary histological architecture, focally mimicking alveolar soft part sarcoma and MiT family translocation renal cell carcinoma. Tumor cells were focally immunoreactive for cytokeratin, S-100, and EMA. RNA sequencing identified a novel in-frame NR1D1 (exon 5)-MAML1 (exon 2) gene rearrangement resulting in the formation of a putative chimeric protein containing the N-terminal C4-type zing finger domains of NR1D1 and the C-terminal MAML1 protein, which was confirmed by subsequent RT-PCR, Sanger sequencing, and FISH assay. To the best of our knowledge, NR1D1-MAML1 fusion has not yet been described in any neoplasms, suggesting the emergence of a novel tumor entity.

Prognostic influence of the treatment approach for pulmonary metastasis in patients with soft tissue sarcoma.

Soft tissue sarcomas (STSs) are rare heterogeneous malignancies of mesenchymal origin. Pulmonary metastases develop in approximately 50% of the patients with high-grade STS, being the major cause of mortality in patients with metastatic STS. Pulmonary metastasectomy has been reported to contribute to long-term survival; however, an appropriate treatment has not been established. We aimed to identify factors associated with post-metastasis survival in STS patients with pulmonary metastasis and determine the appropriate treatment for each patient. We retrospectively reviewed the records of metastatic STS patients treated between 2000 and 2017 and analyzed the clinico-pathologic variables to identify factors associated with the survival. The median survival after pulmonary metastasis was 20.6 months, and the 1-, 3-, and 5-year survival rates were 68.6%, 36.0%, and 25.1%, respectively. The survival was significantly greater in patients who underwent pulmonary metastasectomy than in those without surgery (38.9 months vs. 10.5 months; p < 0.0001). Among those who did not undergo surgery, the survival was significantly greater in patients who received chemotherapy than in those without chemotherapy (19.1 months vs. 6.3 months, p = 0.037). Multivariate analysis identified pulmonary metastasectomy as the most important prognostic factor for post-metastasis survival (Hazard ratio 5.623; 95% Confidence Interval 2.733-11.572; p < 0.0001). In conclusion, pulmonary metastasectomy was the most important prognostic factor for post-metastasis survival in patients with metastatic STS. In addition, chemotherapy could prolong survival in patients who were not eligible for pulmonary resection. Although we should carefully weigh the risks and benefits, appropriate treatment for pulmonary metastases could contribute to long-time survival.

A novel EWSR1-VGLL1 gene fusion in a soft tissue malignant myoepithelial tumor.

Soft tissue myoepithelial tumors are very rare mesenchymal tumors that are currently categorized as miscellaneous neoplasms with uncertain differentiation. Although the molecular pathogenesis of soft tissue myoepithelial tumors remains unclear, EWSR1 gene fusions with a variety of partner genes are regarded as one of the major pathogenic driver events in these tumors. We herein present a case of a deep soft tissue malignant myoepithelial tumor arising in the thigh with multiple pulmonary metastases. This tumor displayed diverse and unique histological features, namely, an epithelioid glandular growth pattern, pseudorosette-like formation, and a diffuse nest and cord-like pattern within an abundant myxoid matrix. Next-generation RNA sequencing identified a novel fusion transcript, in which the in-frame junctional reads contained exon 9 of EWSR1 and exon 2 of VGLL1, resulting in the formation of a putative chimeric protein with the N-terminal transcriptional activation domain of EWSR1 and C-terminal full length of the VGLL1 protein. EWSR1-VGLL1 fusion has not been described in neoplasm before. Further molecular and functional experiments on the present EWSR1-VGLL1 fusion gene are required to elucidate its tumorigenic effect.

Gemcitabine and docetaxel combination chemotherapy for advanced bone and soft tissue sarcomas: protocol for an open-label, non-randomised, Phase 2 study.

BACKGROUND: The prognosis of patients with metastatic or advanced sarcomas is poor and there are few options for treatment. Several studies have shown that gemcitabine and docetaxel (GD) combination chemotherapy has antitumor activity against various subtypes of sarcoma. Recently, some studies have shown a favourable outcome for GD combination chemotherapy for relapsed high-grade osteosarcoma and spindle cell sarcoma of bone. If the effectiveness of GD is proven, this will result in new treatment options for advanced bone and soft tissue sarcomas (STS). The aim of this prospective Phase 2 study is to evaluate the efficacy and toxicity of the GD combination in patients with advanced bone sarcomas and STS. METHODS: This is a Phase 2, single-arm, open-label study to investigate the efficacy and safety of combination chemotherapy with GD for advanced bone sarcomas and STS and will enrol 20 patients. The patients will receive gemcitabine 900 mg/m2 on Days 1 and 8, and docetaxel 70 mg/m2 on Day 8 in 3-week cycles until disease progression or other evidence of treatment failure. The primary aim of this study is to analyse GD's effect on progression-free survival (PFS). The secondary objectives are to analyse treatment efficacy and safety in terms of response rate, tumour control rate, overall survival, and adverse event rate. The length of follow-up will be 5 years. DISCUSSION: This study will evaluate the efficacy and safety of combination therapy with gemcitabine and docetaxel for bone sarcomas and STS. If this combination proves to be acceptable, it could be used for as second, third, or later line therapy for patients with sarcomas (especially bone sarcomas). In the future, the role of various treatments, including GD therapy, will be clarified for specific subtypes of sarcoma. TRIAL REGISTRATION: This study was registered as UMIN000031004 (University Hospital Medical Information Network-Clinical Trial Registry: UMIN-CTR) on 1 March 1 2018 and with the Japan Registry of Clinical Trials (jRCT) as jRCTs051180042 on 30 January 2019. The posted information will be updated as needed to reflect protocol amendments and study progress.

Rescue of ankylosing hip following open reduction and internal fixation of acetabular fracture by surgical resection of heterotopic ossification: A case report.

INTRODUCTION: Heterotopic ossification is a major complication after surgical treatment of acetabular fractures. Heterotopic ossification generally involves the large joints, often limits the range of motion, and may cause ankylosis. PRESENTATION OF CASE: This case report describes a 59-year-old man with severe heterotopic ossification who developed an acetabular fracture and resultant hip ankylosis, which was rescued by surgical resection of the heterotopic ossification. He had accompanying head injury and multiple other fractures, which were treated conservatively. Open reduction with internal fixation of the acetabular fracture was performed through the ilioinguinal and Kocher-Langenbeck combined approach. The patient unexpectedly returned to our hospital 7.5 months after the fracture surgery. We found that his left hip joint was completely ankylosed by severe heterotopic ossification. We performed surgical resection of the heterotopic ossification through a direct lateral approach 9.5 months after the initial surgery. At the final follow-up, 5.5 years after the heterotopic ossification resection surgery, the hip function including the range of motion was satisfactory. Radiographs showed no signs of recurrence, and he could walk with no support. DISCUSSION: The only effective treatment for established HO is surgical excision. Whether delayed or early surgical resection of heterotopic ossification is more effective remains controversial. CONCLUSION: We considered that waiting for a long time before surgical resection of the heterotopic ossification would lead to more disability, and early resection of the heterotopic ossification was not a contraindication despite the fact that the uptake on the bone scan was still intense.

Anterior Cruciate Ligament-Derived Stem Cells Transduced With BMP2 Accelerate Graft-Bone Integration After ACL Reconstruction.

BACKGROUND: Strong graft-bone integration is a prerequisite for successful graft remodeling after reconstruction of the anterior cruciate ligament (ACL) using soft tissue grafts. Novel strategies to accelerate soft tissue graft-bone integration are needed to reduce the need for bone-tendon-bone graft harvest, reduce patient convalescence, facilitate rehabilitation, and reduce total recovery time after ACL reconstruction. HYPOTHESIS: The application of ACL-derived stem cells with enhanced expression of bone morphogenetic protein 2 (BMP2) onto soft tissue grafts in the form of cell sheets will both accelerate and improve the quality of graft-bone integration after ACL reconstruction in a rat model. STUDY DESIGN: Controlled laboratory study. METHODS: ACL-derived CD34+ cells were isolated from remnant human ACL tissues, virally transduced to express BMP2, and embedded within cell sheets. In a rat model of ACL injury, bilateral single-bundle ACL reconstructions were performed, in which cell sheets were wrapped around tendon autografts before reconstruction. Four groups containing a total of 48 rats (96 knees) were established (n = 12 rats; 24 knees per group): CD34+BMP2 (100%), CD34+BMP2 (25%), CD34+ (untransduced), and a control group containing no cells. Six rats from each group were euthanized 2 and 4 weeks after surgery, and each graft was harvested for immunohistochemical and histological analyses. The remaining 6 rats in each group were euthanized at 4 and 8 weeks to evaluate in situ tensile load to failure in each femur-graft-tibia complex. RESULTS: In vitro, BMP2 transduction promoted the osteogenic differentiation of ACL-derived CD34+ cells while retaining their intrinsic multipotent capabilities. Osteoblast densities were greatest in the BMP2 (100%) and BMP2 (25%) groups. Bone tunnels in the CD34+BMP2 (100%) and CD34+BMP2 (25%) groups had the smallest cross-sectional areas according to micro-computed tomography analyses. Graft-bone integration occurred most rapidly in the CD34+BMP2 (25%) group. Tensile load to failure was significantly greater in the groups containing stem cells at 4 and 8 weeks after surgery. Tensile strength was greatest in the CD34+BMP2 (100%) group at 4 weeks, and in the CD34+BMP2 (25%) group at 8 weeks. CONCLUSION: ACL-derived CD34+ cells transduced with BMP2 accelerated graft-bone integration after ACL reconstruction using soft tissue autografts in a rat model, as evidenced by improved histological appearance and graft-bone interface biology along with tensile load to failure at each time point up to 8 weeks after surgery. CLINICAL RELEVANCE: A primary disadvantage of using soft tissue grafts for ACL reconstruction is the prolonged time required for bony ingrowth, which delays the initiation of midsubstance graft remodeling. The lack of consistent correlation between the appearance of a "healed" ACL on postoperative magnetic resonance imaging and readiness to return to sport results in athletes being released to sport before the graft is ready to handle high-intensity loading. Therefore, it is desirable to identify strategies that accelerate graft-bone integration, which would reduce the time to biologic fixation, improve the reliability of biologic fixation, allow for accelerated rehabilitation, and potentially reduce the incidence of early graft pullout and late midsubstance failure.

Therapeutic Potential of Endothelial Progenitor Cells in the Field of Orthopaedics.

Inadequate blood supply frequently impedes the viability of tissue-engineered constructs in the initial phase after implantation, and can lead to improper cell integration or cell death. Vascularization using stem cells has continued to evolve as a potential solution to this problem. In this review, we summarize studies that utilize endothelial progenitor cells (EPCs) for musculoskeletal regeneration. This review will also highlight recent concepts for EPC identification in conjunction with the development of EPC biology research. EPCs promote bone regeneration in animal models through a variety of mechanisms. By differentiating toward endothelial cell lineages and osteoblasts, EPCs stimulate vasculogenesis, angiogenesis and osteogenesis. Moreover, EPCs influence supporting cells through the secretion of growth factors and cytokines. Phase I/II clinical trials have applied circulating CD34+ cells/EPCs to nonunion bone fractures and have exhibited promising results including accelerated bone healing. Similar mechanisms of angiogenesis and osteogenesis are proposed for anterior cruciate ligament (ACL) ruptured tissue derived CD34+ cells, and thus EPCs have implied a critical role at the site of tendon-bone integration. EPCs are an emerging strategy among other cell-based therapies in the field of orthopaedics for the promotion of musculoskeletal regeneration.

The Combined Use of Losartan and Muscle-Derived Stem Cells Significantly Improves the Functional Recovery of Muscle in a Young Mouse Model of Contusion Injuries.

BACKGROUND: Although muscle injuries tend to heal uneventfully in most cases, incomplete functional recovery commonly occurs as a result of scar tissue formation at the site of injury, even after treatment with muscle-derived stem cells (MDSCs). HYPOTHESIS: The transplantation of MDSCs in the presence of a transforming growth factor ß1 (TGF-ß1) antagonist (losartan) would result in decreased scar tissue formation and enhance muscle regeneration after contusion injuries in a mouse model. STUDY DESIGN: Controlled laboratory study. METHODS: An animal model of muscle contusion was developed using the tibialis anterior muscle in 48 healthy mice at 8 to 10 weeks of age. After sustaining muscle contusion injuries, the mice were divided into 4 groups: (1) saline injection group (control group; n = 15), (2) MDSC transplantation group (MDSC group; n = 15), (3) MDSC transplantation plus oral losartan group (MDSC/losartan group; n = 15), and (4) healthy uninjured group (healthy group; n = 3). Losartan was administrated systemically beginning 3 days after injury and continued until the designated endpoint (1, 2, or 4 weeks after injury). MDSCs were transplanted 4 days after injury. Muscle regeneration and fibrotic scar formation were evaluated by histology, and the expression of follistatin, MyoD, Smad7, and Smad2/3 were analyzed by immunohistochemistry and reverse transcription polymerase chain reaction analysis. Functional recovery was measured via electrical stimulation of the peroneal nerve. RESULTS: When compared with MDSC transplantation alone, MDSC/losartan treatment resulted in significantly decreased scar formation, an increase in the number of regenerating myofibers, and improved functional recovery after muscle contusions. In support of these findings, the expression levels of Smad7 and MyoD were significantly increased in the group treated with both MDSCs and losartan. CONCLUSION: When compared with MDSCs alone, the simultaneous treatment of muscle contusions with MDSCs and losartan significantly reduced scar formation, increased the number of regenerating myofibers, and improved the functional recovery of muscle; these effects were caused, at least in part, by the losartan-mediated upregulation of Smad7 and MyoD. Increased levels of Smad7 and MyoD together reduced the deposition of scar tissue (via the inhibition of TGF-ß1 by Smad7) and committed the transplanted MDSCs toward a myogenic lineage (via Smad7-regulated MyoD expression). CLINICAL RELEVANCE: The study findings contribute to the development of biological treatments to accelerate and improve the quality of muscle healing after injury.

Acute Popliteal Artery Occlusion after Revision Total Knee Arthroplasty.

Acute arterial occlusions are a rare complication of total knee arthroplasty (TKA). However, in revision TKA, the risk of such complications is higher and these complications can lead to amputation if not adequately treated. We describe a case of acute popliteal artery occlusion 4 hours after second revision TKA in a patient with a history of several surgical procedures because of periprosthetic infection at a previous hospital. Revascularization was achieved via bypass grafting and amputation was narrowly avoided despite time lag after symptom onset to revascularization. In this case, it was possible that the arterial disease that accompanied the vascular endothelium injury such as pseudoaneurysm had existed since the previous surgery at another hospital and was destroyed by the surgical procedure, which led to the formation of thrombosis and arterial occlusion. Preoperative evaluation of the arterial condition should be considered to avoid acute arterial occlusive disease, especially in patients who had several previous surgical procedures.

The effect of blocking angiogenesis on anterior cruciate ligament healing following stem cell transplantation.

Ruptured human anterior cruciate ligaments (ACL) contain vascular stem cells capable of enhancing the healing of tendon grafts. In the current study we explored the role that neo-angiogenesis plays in ACL healing. ACL-derived CD34+ cells were isolated via Fluorescence Activated Cell Sorting (FACS) from the rupture sites of human ACLs. The cells were then virally transduced to express either vascular endothelial growth factor (VEGF) or soluble FLT-1 (sFLT-1), which is an antagonist of VEGF. We established five groups: CD34+VEGF(100%), where 100% of the cells were transduced with VEGF, CD34+VEGF(25%), where only 25% of the cells were transduced with VEGF, CD34+, CD34+sFLT-1, and a No cells group. The CD34+sFLT1 group had a significant reduction in biomechanical strength compared to the CD34+ group at 4 and 8 weeks; whereas the biomechanical strength of the CD34+VEGF(25%) group was significantly greater than the CD34+ group at week 4; however, no difference was observed by week 8. Immunohistochemical staining demonstrated a significantly lower number of isolectin B4 and hCD31 positive cells, markers associated with angiogenesis, in the CD34+sFLT1 group, and a higher number of isolectin B4 and hCD31 positive cells in the CD34+VEGF(100%) and CD34+VEGF(25%) groups compared to the CD34+ group. Graft maturation was significantly delayed in the CD34+sFLT1 group and accelerated in the CD34+VEGF(25%) group compared to the CD34+ group. In conclusion, blocking VEGF reduced angiogenesis, graft maturation and biomechanical strength following ACL reconstruction. Native expression of VEGF by the CD34+ cells improved tendon graft maturation and biomechanical strength; however, over-expression of VEGF impeded improvements in biomechanical strength.

Tissue engineering of ligaments for reconstructive surgery.

PURPOSE: The use of musculoskeletal bioengineering and regenerative medicine applications in orthopaedic surgery has continued to evolve. The aim of this systematic review was to address tissue-engineering strategies for knee ligament reconstruction. METHODS: A systematic review of PubMed/Medline using the terms "knee AND ligament" AND "tissue engineering" OR "regenerative medicine" was performed. Two authors performed the search, independently assessed the studies for inclusion, and extracted the data for inclusion in the review. Both preclinical and clinical studies were reviewed, and the articles deemed most relevant were included in this article to provide relevant basic science and recent clinical translational knowledge concerning "tissue-engineering" strategies currently used in knee ligament reconstruction. RESULTS: A total of 224 articles were reviewed in our initial PubMed search. Non-English-language studies were excluded. Clinical and preclinical studies were identified, and those with a focus on knee ligament tissue-engineering strategies including stem cell-based therapies, growth factor administration, hybrid biomaterial, and scaffold development, as well as mechanical stimulation modalities, were reviewed. CONCLUSIONS: The body of knowledge surrounding tissue-engineering strategies for ligament reconstruction continues to expand. Presently, various tissue-engineering techniques have some potential advantages, including faster recovery, better ligamentization, and possibly, a reduction of recurrence. Preclinical research of these novel therapies continues to provide promising results. There remains a need for well-designed, high-powered comparative clinical studies to serve as a foundation for successful translation into the clinical setting going forward. LEVEL OF EVIDENCE: Level IV, systematic review of Level IV studies.