Damir Hudetz

Articular cartilage repair by genetically modified bone marrow aspirate in sheep

Bone marrow presents an attractive option for the treatment of articular cartilage defects as it is readily accessible, it contains mesenchymal progenitor cells that can undergo chondrogenic differentiation and, once coagulated, it provides a natural scaffold that contains the cells within the defect. This study was performed to test whether an abbreviated ex vivo protocol using vector-laden, coagulated bone marrow aspirates for gene delivery to cartilage defects may be feasible for clinical application. Ovine autologous bone marrow was transduced with adenoviral vectors containing cDNA for green fluorescent protein or transforming growth factor (TGF)-β1. The marrow was allowed to clot forming a gene plug and implanted into partial-thickness defects created on the medial condyle. At 6 months, the quality of articular cartilage repair was evaluated using histological, biochemical and biomechanical parameters. Assessment of repair showed that the groups treated with constructs transplantation contained more cartilage-like tissue than untreated controls. Improved cartilage repair was observed in groups treated with unmodified bone marrow plugs and Ad.TGF-β1-transduced plugs, but the repaired tissue from TGF-treated defects showed significantly higher amounts of collagen II (P<0.001). The results confirmed that the proposed method is fairly straightforward technique for application in clinical settings. Genetically modified bone marrow clots are sufficient to facilitate articular cartilage repair of partial-thickness defects in vivo. Further studies should focus on selection of transgene combinations that promote more natural healing.

Regenerative medicine and tissue engineering in orthopaedic surgery.

Orthopedic surgery is going through a serious paradigm shift ; instead of simply replacing damaged tissues with prosthetic or allograft material, the aim is to regenerate them. This endeavor has generated the field of regenerative orthopaedics, an increasingly expanding area of research with hopes of providing new and better treatments for diseases and injuries affecting the musculoskeletal system. As part of this process, we are witnessing a substantial accumulation of new cellular and molecular insights into connective tissue function, coupled with emerging new concepts in stem cell biology and scaffolding technologies. Indeed, any successful strategy to regenerate musculoskeletal tissues can be portrayed as an intricate interplay between the three main constituents of the regenerative system: cells, environment and scaffolds. This review is not meant to be exhaustive and comprehensive, but aims to highlight concepts and key advances in the field of regenerative orthopaedics and tissue engineering, as well as to present current possibilities for clinical translation.Orthopedic surgery is going through a serious paradigm shift; instead of simply replacing damaged tissues with prosthetic or allograft material, the aim is to regenerate them. This endeavor has generated the field of regenerative orthopaedics, an increasingly expanding area of research with hopes of providing new and better treatments for diseases and injuries affecting the musculoskeletal system. As part of this process, we are witnessing a substantial accumulation of new cellular and molecular insights into connective tissue function, coupled with emerging new concepts in stem cell biology and scaffolding technologies. Indeed, any successful strategy to regenerate musculoskeletal tissues can be portrayed as an intricate interplay between the three main constituents of the regenerative system: cells, environment and scaffolds. This review is not meant to be exhaustive and comprehensive, but aims to highlight concepts and key advances in the field of regenerative orthopaedics and tissue engineering, as well as to present current possibilities for clinical translation.

Nanobiotechnology and bone regeneration: a mini-review

The purpose of this paper is to review current developments in bone tissue engineering, with special focus on the promising role of nanobiotechnology. This unique fusion between nanotechnology and biotechnology offers unprecedented possibilities in studying and modulating biological processes on a molecular and atomic scale. First we discuss the multiscale hierarchical structure of bone and its implication on the design of new scaffolds and delivery systems. Then we briefly present different types of nanostructured scaffolds, and finally we conclude with nanoparticle delivery systems and their potential use in promoting bone regeneration. This review is not meant to be exhaustive and comprehensive, but aims to highlight concepts and key advances in the field of nanobiotechnology and bone regeneration.

The Effect of Intra-articular Injection of Autologous Microfragmented Fat Tissue on Proteoglycan Synthesis in Patients with Knee Osteoarthritis

Osteoarthritis (OA) is one of the leading musculoskeletal disorders in the adult population. It is associated with cartilage damage triggered by the deterioration of the extracellular matrix tissue. The present study explores the effect of intra-articular injection of autologous microfragmented adipose tissue to host chondrocytes and cartilage proteoglycans in patients with knee OA. A prospective, non-randomized, interventional, single-center, open-label clinical trial was conducted from January 2016 to April 2017. A total of 17 patients were enrolled in the study, and 32 knees with osteoarthritis were assessed. Surgical intervention (lipoaspiration) followed by tissue processing and intra-articular injection of the final microfragmented adipose tissue product into the affected knee(s) was performed in all patients. Patients were assessed for visual analogue scale (VAS), delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and immunoglobulin G (IgG) glycans at the baseline, three, six and 12 months after the treatment. Magnetic resonance sequence in dGEMRIC due to infiltration of the anionic, negatively charged contrast gadopentetate dimeglumine (Gd-DTPA2−) into the cartilage indicated that the contents of cartilage glycosaminoglycans significantly increased in specific areas of the treated knee joint. In addition, dGEMRIC consequently reflected subsequent changes in the mechanical axis of the lower extremities. The results of our study indicate that the use of autologous and microfragmented adipose tissue in patients with knee OA (measured by dGEMRIC MRI) increased glycosaminoglycan (GAG) content in hyaline cartilage, which is in line with observed VAS and clinical results.

Gene therapy applications in orthopaedics.

Dear Editor, With great interest and enthusiasm, we read the article “Orthopaedic applications of gene therapy“ [1]. The authors should be congratulated for their concise yet very thorough and excellent coverage of the gene therapy applications in orthopaedics. However, it is our opinion that articular cartilage deserved more of their attention. Primarily, we think that the subsection heading “Cartilage repair” should be expanded to “Cartilage repair and regeneration”, particularly since the authors did mention “stimulation of cartilage regeneration” which implies the possibility of inducing intrinsic healing of the damaged cartilage by hyaline cartilage formation. When treating localised cartilage defects we should ask ourselves: What kind of new tissue formation inside the defect do we want to induce? Ideally we aim for articular cartilage regeneration, not repair, which would mean formation of hyaline cartilage, not fibrocartilage. Treatment options published in the literature can be roughly divided into two concepts—reparative and restorative. The end result of the first concept is fibrocartilage, and the microfracture technique is the most popular representative. In contrast, the restorative concept aims for hyaline cartilage implantation/formation and includes implantation of osteochondral plugs with perfectly organised cartilage and matrix and/or cell therapy, namely autologous chondrocyte transplantation. Anabolic factors including members of the TGF-beta superfamily, such as BMPs, have proven their potential to stimulate chondrogenesis and synthesis of cartilage-specific matrix components in animal models [2, 3]. However, those proteins have short half-lives and it is difficult to maintain adequate in situ concentrations necessary for their proper functioning. Furthermore, many proteins act intracellularly and because cells cannot normally import these proteins, they cannot be used in soluble forms. These problems are the reason why gene therapy has attracted so much attention lately. The transfer of the respective genes into the joint, possibly in combination with the supply of chondroprogenitor cells, might be an elegant method to achieve a sustained delivery of such therapeutic factors at the required location in vivo [4]. Pascher et al. [5] developed a novel ex vivo method by using coagulated bone marrow aspirate as a mean of gene delivery to cartilage. Vector-seeded and cell-seeded bone marrow clots (“gene plugs”) were found to maintain their structural integrity following extensive culture and maintained transgenic expression for several weeks. Therefore, we conclude that there is a huge potential for new tissue formation by gene therapy trandsuction of cells of different origin. Cells originating subchondrally, in combination with gene therapy, may form tissue of higher quality than is achieved with the classical microfracture technique. On the other hand, hyaline cartilage formation by gene therapy induction in combination with cell implantation (possibly on biodegradable scaffolds) might be the answer to the current limitations of cartilage treatment modalities, and may provide permanent solution for the patients. Many animal studies are currently underway to investigate gene therapy-induced cartilage regeneration of chondral and osteochondral defects, and some of these investigations can be expected to lead to clinical trials and yield answers to these open questions.

Acute hyperextension/valgus trauma to the elbow in top-level adult male water polo goalkeepers: a cause of osteochondritis disecans of the capitellum?

We report on 2 cases of hyperextension/valgus elbow injuries in two adult male national team water polo goalkeepers. Both were healthy and had never sustained any major injuries of the elbow. Mechanism and type of injury in both of them was identical. Different medical treatment protocols of these injuries possibly have led to different outcomes, with one of them developing osteochondritis dissecans (OCD). Inadequate medical treatment of acute impact elbow injuries could lead to osteochondritis disecans of the elbow in top-level adult male water polo goalkeepers.