Arthroscopic Capsulodesis for the Treatment of Dynamic Scapholunate Dissociations.

Management of scapholunate dissociations remains a significant challenge. Open approaches suffer from a disadvantageous further impairment of the stabilizing local structures. The minimally invasive arthroscopic technique described provides reliable stability of the scapholunate interosseous ligament complex in dynamic lesions. The anatomic key structure is the dorsal capsuloligamentous scapholunate septum, which provides a mechanical connection between the scaphoid, lunate, and dorsal capsule of the wrist. Arthroscopic capsuloplasty aims to tighten and stabilize this complex structure in long term. This approach preserves the adjacent structures, namely the secondary wrist stabilizers and their neuromuscular feedback loops. With a certain degree of experience in wrist arthroscopy, the technique is reliably adaptable and reproducible.

Ulnocarpal Impaction.

Ulnocarpal impaction syndrome is a common cause for ulnarsided wrist pain caused by an abutment between the ulnar head and the lunotriquetral complex. This pain is typically triggered by load bearing and rotation of the forearm. Radiographic examination is often associated with positive ulnar variance and cysts in the lunate, edema of the ulnoproximal lunate is shown in MRI. Operative treatment aims to reduce load on the lunate, either by open ulnar shortening osteotomy or arthroscopic wafer procedure.

Overexpression of hypoxia-inducible factor-1 alpha improves vasculogenesis-related functions of endothelial progenitor cells.

Postnatal vasculogenesis is mediated by mobilization of endothelial progenitor cells (EPCs) from bone marrow and homing to ischemic tissues. This feature emphasizes this cell type for cell-based therapies aiming at the improvement of neovascularization in tissue engineering applications and regenerative medicine. In animal models, it was demonstrated that implantation of EPCs from cord blood (cbEPCs) led to the formation of a complex functional neovasculature, whereas EPCs isolated from adult peripheral blood (pbEPCs) showed a limited vasculogenic potential, which may be attributed to age-related dysfunction. Recently, it was demonstrated that activation of hypoxia-inducible factor-1α (Hif-1α) improves cell functions of progenitor cells of mesenchymal and endothelial origin. Thus, we hypothesized that overexpression of Hif-1α may improve the vasculogenesis-related phenotype of pbEPCs. In the present study, we overexpressed Hif-1α in pbEPCs and cbEPCs by using recombinant adenoviruses and investigated effects on stem cell- and vasculogenesis-related cell parameters. Overexpression of Hif-1α enhanced proliferation, invasion, cell survival and in vitro capillary sprout formation of both EPC populations. Migration was increased in cbEPCs upon Hif-1α overexpression, but not in pbEPCs. Cellular senescence was decreased in pbEPCs, while remained in cbEPCs, which showed, as expected, intrinsically a dramatically lower senescent phenotype in relation to pbEPCs. Similarly, the colony-formation capacity was much higher in cbEPCs in comparison to pbEPCs and was further increased by Hif-1α overexpression, whereas Hif-1α transduction exerted no significant influence on colony formation of pbEPCs. In summary, our experiments illustrated multifarious effects of Hif-1α overexpression on stem cell and vasculogenic parameters. Therefore, Hif-1α overexpression may represent a therapeutic option to improve cellular functions of adult as well as postnatal EPCs.

Transcriptomic Changes in Osteoblasts Following Endothelial Cell-Cocultivation Suggest a Role of Extracellular Matrix in Cellular Interaction.

Vascularization is important for bone development, fracture healing and engineering of artificial bone tissue. In the context of bone tissue engineering, it was shown that coimplantation of human primary umbilical vein endothelial cells (HUVECs) and human osteoblasts (hOBs) results in the formation of functional blood vessels and enhanced bone regeneration. Implanted endothelial cells do not only contribute to blood vessel formation, but also support proliferation, cell survival and osteogenic differentiation of coimplanted hOBs. These effects are partially mediated by direct heterotypic cell contacts. In a previous report we could show that cocultivated hOBs strongly increase the expression of genes involved in extracellular matrix (ECM) formation in HUVECs, suggesting that ECM may be involved in the intercellular communication between hOBs and HUVECs. The present study aimed at investigating whether comparable changes occur in hOBs. We therefore performed a microarray analysis of hOBs cultivated in direct contact with HUVECs, revealing 1,004 differentially expressed genes. The differentially expressed genes could be assigned to the functional clusters ECM, proliferation, apoptosis and osteogenic differentiation. The microarray data could be confirmed by performing quantitative real time RT-PCR on selected genes. Furthermore, we could show that the ECM produced by HUVECs increased the expression of the osteogenic differentiation marker alkaline phosphatase (ALP) in hOBs. In summary, our data demonstrate that HUVECs provoke complex changes in gene expression patterns in cocultivated hOBs and that ECM plays and important role in this interaction. J. Cell. Biochem. 117: 1869-1879, 2016. © 2016 Wiley Periodicals, Inc.

Utilization of a genetically modified muscle flap for local BMP-2 production and its effects on bone healing: a histomorphometric and radiological study in a rat model.

AIM OF THE STUDY: We developed an experimental rat model to explore the possibility of enhancing the healing of critical-size bone defects. The aim of this study was to demonstrate the feasibility of this concept by achieving high local BMP-2 expression via a transduced muscle flap that would facilitate bony union while minimizing systemic sequelae. METHODS: The transduction potential of the adenoviral vector encoding for BMP-2 was tested in different cell lines in vitro. In vivo experiments consisted of harvesting a pedicled quadriceps femoris muscle flap with subsequent creation of a critical-size defect in the left femur in Sprague-Dawley rats. Next, the pedicled muscle flap was perfused with high titers of Ad.BMP-2 and Ad.GFP virus, respectively. Twelve animals were divided into three groups comparing the effects of Ad.BMP-2 transduction to Ad.GFP and placebo. Bone healing was monitored radiologically with subsequent histological analysis post-mortem. RESULTS: The feasibility of this concept was demonstrated by successful transduction in vitro and in vivo as evidenced by a marked increase of BMP-2 expression. The three examined groups only showed minor difference regarding bone regeneration; however, one complete bridging of the defect was observed in the Ad.BMP-2 group. No evidence of systemic viral contamination was noted. CONCLUSIONS: A marked increase of local BMP-2 expression (without untoward systemic sequelae) was detected. However, bone healing was not found to be significantly enhanced, possibly due to the small sample size of the study.

Cell-assisted lipotransfer.

BACKGROUND: Because of their easy accessibility and versatile biological properties, mesenchymal stem cells taken from fatty tissue (adipose-derived stem cells, ADSC) are attractive for various potential clinical uses. For example, ADSC can be added to fatty tissue before transplantation in the hope of improving the outcome of autologous lipotransfer: the modified procedure is called cell-assisted lipotransfer. The clinical use and commercial promotion of this novel stem-cell treatment (and others) are spreading rapidly, even though there is not yet any clear clinical evidence for its safety and efficacy. METHODS: In cooperation with the German Cochrane Center, we systematically searched the literature according to the PRISMA criteria. Eight major medical databases were searched. The retrieved publications were examined by two independent reviewers and assessed using objective criteria. RESULTS: After screening of the 3161 retrieved publications by title, abstract, and (where appropriate) full text, 78 were still considered relevant. 13 of these were reports of clinical studies; only 3 of the 13 met criteria for grade II or III evidence. The studies that were analyzed involved a total of 286 cell-assisted lipotransfer procedures with a longest follow-up time of 42 months. Oncological safety was not demonstrated. CONCLUSION: The studies published to date have not shown that cell-assisted lipotransfer is generally superior to conventional autologous lipotransfer. They dealt with safety aspects inappropriately or not at all. The case of cell-assisted lipotransfer illustrates the indispensability of high-quality clinical evidence before the introduction of novel stem-cell-based treatments.

Up-regulation of alkaline phosphatase expression in human primary osteoblasts by cocultivation with primary endothelial cells is mediated by p38 mitogen-activated protein kinase-dependent mRNA stabilization.

For the regeneration of bone in tissue engineering applications, it is essential to provide cues that support neovascularization. This can be achieved by cell-based therapies using mature endothelial cells (ECs) or endothelial progenitor cells. In this context, ECs were used in various in vivo studies in combination with primary osteoblasts to enhance neovascularization of bone grafts. In a previous study, we have shown that cocultivation of human primary ECs and human primary osteoblasts (hOBs) leads to a cell contact-dependent up-regulation of alkaline phosphatase (ALP) expression in osteoblasts, indicating that cocultivated ECs may support osteogenic differentiation and osteoblastic cell functions. In the present study, we investigated this effect in more detail, revealing a time and cell number dependency of EC-mediated up-regulation of the early osteoblastic marker ALP, whereas osteocalcin, a late marker of osteogenesis, was down-regulated. The effect on ALP expression was bidirectional specific for both cell types. Functional inhibition of gap junctional communication between ECs and hOBs by 18alpha-glycyrrhetinic acid had only a weak suppressive effect on EC-mediated ALP up-regulation. In contrast, inhibition of p38 mitogen-activated protein kinase nearly completely prevented the EC-mediated stimulation of osteoblastic ALP expression. To investigate the molecular mechanism underlying the ALP up-regulation, we examined the effect of EC cocultivation on osteoblastic ALP promoter activity as well as mRNA stability. Cocultivation of ECs with hOBs significantly elevated the half-life of osteoblastic ALP mRNA without affecting its promoter activity. In summary, our data show that EC-mediated up-regulation of osteoblastic ALP expression is cell-type specific and is posttranscriptionally regulated via p38 mitogen-activated protein kinase-dependent mRNA turn-over.

"Turnover proteome" of human atrial trabeculae.

Most of the biologically relevant data on cardiomyocytes are derived from isolated cells under conditions that are, to some extent, altered compared to the natural milieu of the functional heart. The handling procedure of the dissection, isolation, and short-term culturing induces changes in the cells such that the subsequently measured parameters (among others, the protein synthesis) reflect the actual experimental conduct rather than the intrinsic properties of these terminally differentiated cells. Although it is known that the protein synthetic machinery of isolated cardiomyocytes is operational and functional, the biosynthetic yield of human cardiomyocytes in the natural milieu of the trabeculae remains to be established, with a special emphasis to clarify whether the protein synthesis includes just a limited set of polypeptides or it encompasses all cellular constituents. Knowledge on this issue is a prerequisite for achieving further advances in our understanding of heart remodeling related to hypertrophy in particular, and for attempting interventions leading to repair of damaged heart in general. The experimental system of "organ bath" enables simultaneous registration of contractile forces of portions of cardiac muscle tissue (and other myocyte-containing tissues) and biosynthetic labeling of newly synthesized cellular constituents. The organ bath methodology was adapted for this project such as enabling to measure molecular changes in response to in vitro applied stimuli. Instead of Krebs-Henseleit-solution, as used in classical protocols of organ bath studies, we utilized cell culture media suitable to experimental conditions related to metabolic labeling. Proteome patterns established by performing two-dimensional gel electrophoresis of the extracts from biosynthetically labeled trabeculae revealed that cardiomyocytes synthesize the full spectrum of cellular proteins. Proteomic silver-stain readout was used to obtain samples for spot excisions, as material suitable for mass spectrometric analysis. Protein spots were identified both from the excised spots and also by matching with the in-house- and www-databases (Swiss-Prot/High-Performance Heart). From our findings that protein synthesis in terminally differentiated cardiomyocytes is not confined just to the synthesis of those structures needed for the post-mitotic house-keeping functions, we conclude that this model might serve as a valid experimental system to study and elucidate the effects of various pharmacological compounds under conditions where physiology (contractile forces) and biochemistry (protein synthesis) of intact human heart tissue are monitored simultaneously.