The Working Group of the German Orthopedic and Trauma Society (DGOU) on Tissue Regeneration has published recommendations on the indication of different surgical approaches for treatment of full-thickness cartilage defects in the knee joint in 2004, 2013 and 2016. Based upon new scientific knowledge and new developments, this recommendation is an update based upon the best clinical evidence available. In addition to prospective randomised controlled clinical trials, this also includes studies with a lower level of evidence. In the absence of evidence, the decision is based on a consensus process within the members of the working group. The principle of making decision dependent on defect size has not been changed in the new recommendation either. The indication for arthroscopic microfracturing has been reduced up to a defect size of 2 cm(2) maximum, while autologous chondrocyte implantation is the method of choice for larger cartilage defects. Additionally, matrix-augmented bone marrow stimulation (mBMS) has been included in the recommendation for defects ranging from 1 to 4.5 cm(2). For the treatment of smaller osteochondral defects, in addition to osteochondral transplantation (OCT), mBMS is also recommended. For larger defects, matrix-augmented autologous chondrocyte implantation (mACI/mACT) in combination with augmentation of the subchondral bone is recommended.

The working group, "Clinical Tissue Regeneration" of the German Society of Orthopedics and Traumatology (DGOU) issues this paper to update their guidelines. Methods Peer-reviewed literature was analyzed regarding different topics relevant to osteochondral lesions of the talus (OLTs) treatment. This process concluded with a statement for each topic reflecting the best scientific evidence available for a particular diagnostic or therapeutic concept, including the grade of recommendation. Besides the scientific evidence, all group members rated the statements to identify possible gaps between literature and current clinical practice. Conclusion In patients with minimal symptoms, OLT progression to ankle osteoarthritis is unlikely. Risk factors for progression are the depth of the lesion on MRI, subchondral cyst formation, and the extent of bone marrow edema. Conservative management is the adaptation of activities to the performance of the ankle joint. A follow-up imaging after 12 months helps not to miss any progression. It is impossible to estimate the probability of success of conservative management from initial symptoms and imaging. Cast immobilization is an option in OLTs in children, with a success rate of approximately 50%, although complete healing, estimated from imaging, is rare. In adults, improvement by conservative management ranges between 45% and 59%. Rest and restrictions for sports activities seem to be more successful than immobilization. Intra-articular injections of hyaluronic acid and platelet-rich plasma can improve pain and functional scores for more than 6 months. If 3 months of conservative management does not improve symptoms, surgery can be recommended.

ZusammenfassungDie Arbeitsgemeinschaft „Klinische Geweberegeneration“ hat bereits in den Jahren 2004, 2013 und 2016 Empfehlungen in Bezug auf die Indikation für verschiedene knorpelregenerative Verfahren zur Behandlung von Knorpelschäden am Kniegelenk publiziert. Auf Basis neuer wissenschaftlicher Erkenntnisse sollen in der vorliegenden Arbeit diese Empfehlungen auch unter Einbeziehung neuer Behandlungsverfahren aktualisiert werden. Die Einschätzung folgt damit dem Prinzip der besten verfügbaren Evidenz und berücksichtigt über prospektiv randomisierte Studien hinaus auch Studien mit niedrigerem Evidenzniveau. An Stellen fehlender publizierter Evidenz basiert die Entscheidung hier auf einem Konsensusprozess innerhalb der Mitglieder der AG Klinische Geweberegeneration.Das Prinzip der bereits vorausgehend publizierten Arbeiten bleibt auch in den neuen Empfehlungen erhalten. Kleine Knorpelschäden sind nach Ansicht der Arbeitsgruppe für eine Knochenmarkstimulation zugänglich, die matrixassoziierte autologe Chondrozytentransplantation (mACT) ist für größere Knorpelschäden die Methode der Wahl. Auf Basis neuerer Daten wird jedoch die Indikationsgrenze für die mACT auf 2,0 cm2 reduziert. Zusätzlich zur arthroskopischen Mikrofrakturierung wird auch die matrixaugmentierte Knochenmarkstimulation in die Empfehlung als Standardverfahren aufgenommen (empfohlene Defektgröße 1–4,5 cm2). Für die Therapie kleinerer osteochondraler Defekte wird neben der osteochondralen Transplantation (OCT) auch die matrixaugmentierte Knochenmarkstimulation empfohlen. Bei größeren Defekten eignet sich die autologe Knorpelzelltransplantation (mACT) in Kombination mit einer Rekonstruktion des subchondralen Knochens.

Autologous chondrocyte transplantation (ACT) is an increasingly used procedure for the surgical repair of full-thickness articular cartilage defects in the knee. For larger defects it is now recommended as a first-line treatment by the respective German professional societies.

Background: Osteochondritis dissecans (OCD) of the knee is a challenging problem. Previously, the authors implemented a novel 1-step surgical procedure for OCD treatment consisting of matrix-associated autologous chondrocyte implantation (ACI) and simultaneous bone reconstruction including the subchondral lamina. Purpose: This study presents the 2-to 5-year results after this technique, assessing correlations of clinical function and cartilage and bone remodeling processes. Study Design: Case series; Level of evidence, 4. Methods: Twenty-six patients with symptomatic condylar knee OCD (International Cartilage Repair Society OCD III/IV) were treated with matrix-associated ACI and monocortical cancellous cylinders for defect filling and subchondral bone plate reconstruction using cortical graft layers as novel subchondral lamina. Evaluations were performed with clinical rating scales and 1.5-T magnetic resonance imaging using the magnetic resonance observation of cartilage repair tissue (MOCART) score and a newly implemented subchondral lamina remodeling grade. Results: The defect size was 5.3 ± 2.3 cm 2 . The defect depth was 8.7 ± 2.4 mm. After a follow-up of 39.8 ± 12.0 months, all scores improved significantly. Nineteen patients (73%) reached good/excellent results in the Lysholm-Gillquist score (preoperatively: 53.2 ± 18.0 points; latest follow-up: 88.5 ± 9.5 points) and the Cincinnati knee rating score (preoperatively: 51.7 ± 13.0 points; latest follow-up: 84.6 ± 11.7 points) and significant improvements in the subjective International Knee Documentation Committee (IKDC) score by 27.9% (preoperatively: 50.5% ± 16.1%; latest follow-up: 78.4% ± 13.4%). The MOCART score reached 62.4 ± 18.9 points. The clinical improvement and tissue remodeling occurred simultaneously and timed; thus, the cartilage defect filling and the lamina remodeling grades correlated significantly with each other, the follow-up time, and almost all clinical scores. Conclusion: The simultaneous reconstruction of deep osteochondral defects of the knee OCD with monocortical cancellous cylinders and matrix-associated ACI is a biological, 1-step alternative to osteochondral cylinder transfer or conventional ACI that leads to good clinical and magnetic resonance imaging results after an intermediate follow-up period. The present study demonstrated simultaneous remodeling processes of articular cartilage repair tissue and subchondral lamina; this synchronization is not yet understood and deserves further investigation.

Mesenchymal stromal cells (MSCs) do not express a unique definite epitope or marker gene. As such, minimal criteria were recently established for defining multipotent MSC. These criteria include expression of CD73, CD90, CD105, and a lack of hematopoietic marker expression. However, we detected binding of a CD14 antibody on bone marrow‐ and placenta‐derived MSC and investigated the staining of CD14 antibodies on these MSC in more detail. The MSC were isolated from human bone marrow and placenta tissue, expanded, characterized by quantitative RT‐PCR, flow cytometry, and immunocytochemistry and differentiated to generate osteoblasts, chondrocytes, and adipocytes. The CD14‐cross‐reactive MSCs were enriched by cell sorting. Human peripheral blood mononuclear cells, fibroblasts, and hematopoietic cell lines served as controls. Utilizing four different clones of CD14 monoclonal antibodies, we found that three CD14 reagents stained the MSC. Two CD14 antibodies (HCD14 and M5E2) clearly marked the CD90+ MSC population with distinct intensities, clone 134 620 generated a shift in flow cytometry histograms, but clone MΦP9 did not stain MSC. Transcripts encoding CD14 or the CD14 protein were not detected in MSC. We confirm that bone marrow‐ and placenta‐derived MSC do not express CD14 and that the CD14 antibody MΦP9 discriminates between monocytes and MSC more efficiently than the other antibodies employed here. This investigation does not contradict previous work but provides a more accurate characterization of MSC. © 2011 International Society for Advancement of Cytometry

BackgroundConventionally, mesenchymal stem cells are functionally isolated from primary tissue based on their capacity to adhere to a plastic surface. This isolation procedure is hampered by the unpredictable influence of co-cultured hematopoietic and/or other unrelated cells and/or by the elimination of a late adhering mesenchymal stem cells subset during removal of undesired cells. To circumvent these limitations, several antibodies have been developed to facilitate the prospective isolation of mesenchymal stem cells. Recently, we described a panel of monoclonal antibodies with superior selectivity for mesenchymal stem cells, including the monoclonal antibodies W8B2 against human mesenchymal stem cell antigen-1 (MSCA-1) and 39D5 against a CD56 epitope, which is not expressed on natural killer cells.Designand Methods Bone marrow derived mesenchymal stem cells from healthy donors were analyzed and isolated by Bow cytometry using a large panel of antibodies against surface antigens including CD271, MSCA-1, and CD56. The growth of mesenchymal stem cells was monitored by colony formation unit fibroblast (CFU-F) assays. The differentiation of mesenchymal stem cells into defined lineages was induced by culture in appropriate media and verified by immunostaining.ResultsMulticolor cell sorting and CFU-F assays showed that mesenchymal stem cells were similar to 90-fold enriched in the MSCA-1(+)CD56(-) fraction and similar to 180-fold in the MSCA-1(+)CD56(+) fraction. Phenotype analysis revealed that the expression of CD10, CD26, CD106, and CD146 was restricted to the MSCA-1(+)CD56(-) mesenchymal stem cells subset and CD166 to MSCA-1(+)CD56(+/-) mesenchymal stem cells. Further differentiation of these subsets showed that chondrocytes and pancreatic-like islets were predominandy derived from MSCA-1(+)CD56(+/-) cells whereas adipocytes emerged exclusively from MSCA-1(+)CD56(-) cells. The culture of single-sorted MSCA-1(+)CD56(+) cells resulted in the appearance of phenotypically heterogeneous clones with distinct proliferation and differentiation capacities.ConclusionsNovel mesenchymal stem cells subsets with distinct phenotypic and functional properties were identified. Our data suggest that the MSCA-1(+)CD56(+) subset is an attractive starting population for autologous chondrocyte transplantation.

Objectives:Mesenchymal stromal cells (MSC) are a promising tool for tissue engineering of the intervertebral disc. The injured tissue is usually characterized by inflammatory processes. In this study we investigated the effect of IL‐1beta on the chondrogenic differentiation of MSC.Methods:Bone‐marrow‐derived MSC were cultured in FCS‐free, GMP‐compatible medium and characterized by flow cytometry. Chondrogenic differentiation of MSC was induced with and without IL‐1beta supplementation. After 28 days, micromasses were analyzed by immunostaining. In addition, the gene expression of several matrix proteins was investigated by quantitative PCR.Results:Micromasses differentiated under IL‐1beta supplementation are characterized by smaller dimensions, disruptions and weaker accumulation and expression of extracellular matrix proteins compared to micromasses differentiated without IL‐1beta supplementation.Conclusion:Inflammatory processes in the injured tissue could inhibit the chondrogenic differentiation of transplanted MSC. For cell therapy to be effective it will be necessary to develop strategies to ensure the steady expression of extracellular matrix proteins under inflammatory conditions.

Full-thickness defects of the articular cartilage in the knee joint have lower regenerative properties than chondral lesions of the ankle. In order to avoid early osteoarthritis, symptomatic articular cartilage defects in younger patients should undergo biological reconstruction as soon as possible. Various surgical procedures are available to biologically resurface the articular joint line. Numerous animal experiments and clinical studies have shown that early biological reconstruction of circumscribed cartilage defects in the knee is superior to conservative or delayed surgical treatment. This superiority refers not only to defect healing but also to the elimination of changes following secondary osteoarthritis. The various surgical procedures can be differentiated by the range of indications and the final outcome. Additional malalignment, meniscus tears and/or ligament instabilities should be treated simultaneously with the cartilage resurfacing. The mid- and long-term results of the various current techniques are promising, but further modifications and improvements are needed.

Osteoarthritis (OA) is a multifactorial disease strongly correlated with history of joint trauma, joint dysplasia, and advanced age. Mesenchymal stem cells (MSCs) are promising cells for biological cartilage regeneration. Conflicting data have been published concerning the availability of MSCs from the iliac crest, depending on age and overall physical fitness. Here, we analyzed whether the availability and chondrogenic differentiation capacity of MSCs isolated from the femoral shaft as an alternative source is age- or OA etiology-dependent. MSCs were isolated from the bone marrow (BM) of 98 patients, categorized into three OA-etiology groups (age-related, joint trauma, joint dysplasia) at the time of total hip replacement. All BM samples were characterized for cell yield, proliferation capacity, and phenotype. Chondrogenic differentiation was studied using micromass culture and analyzed by histology, immunohistochemistry, and quantitative reverse transcriptase-polymerase chain reaction. Significant volumes of viable BM (up to 25 ml) could be harvested from the femoral shaft without observing donor-site morbidity, typically containing >10(7) mononuclear cells per milliliter. No correlation of age or OA etiology with the number of mononuclear cells in BM, MSC yield, or cell size was found. Proliferative capacity and cellular spectrum of the harvested cells were independent of age and cause of OA. From all tested donors, MSCs could be differentiated into the chondrogenic lineage. We conclude that, irrespective of age and OA etiology, sufficient numbers of MSCs can be isolated and that these cells possess an adequate chondrogenic differentiation potential. Therefore, a therapeutic application of MSCs for cartilage regeneration of OA lesions seems feasible. Disclosure of potential conflicts of interest is found at the end of this article.

The isolation of mesenchymal stem cells (MSC) from primary tissue is hampered by the limited selectivity of available markers. So far, CD271 is one of the most specific markers for bone marrow (BM)-derived MSC. In search of additional markers, monoclonal antibodies (mAbs) with specificity for immature cells were screened by flow cytometry for their specific reactivity with the rare CD271(+) population. The recognized CD271(+) populations were fractionated by fluorescence-activated cell sorting and the clonogenic capacity of the sorted cells was analyzed for their ability to give rise to CFU-F. The results showed that only the CD271(bright) but not the CD271(dim) population contained CFU-F. Two-color flow cytometry analysis revealed that only the CD271(bright) population was positive for the established MSC markers CD10, CD13, CD73, and CD105. In addition, a variety of mAbs specific for novel and partially unknown antigens selectively recognized the CD271(bright) population but no other BM cells. The new MSC-specific molecules included the platelet-derived growth factor receptor-beta (CD140b), HER-2/erbB2 (CD340), frizzled-9 (CD349), the recently described W8B2 antigen, as well as cell-surface antigens defined by the antibodies W1C3, W3D5, W4A5, W5C4, W5C5, W7C6, 9A3, 58B1, F9-3C2F1, and HEK-3D6. In conclusion, the described markers are suitable for the prospective isolation of highly purified BM-MSC. These MSC may be used as an improved starting population for transplantation in diseases like osteogenesis imperfecta, cartilage repair, and myocardial infarction.

Die Arthroskopie ist heutzutage ein fester Bestandteil der Therapie intraartikulärer Erkrankungen. Insbesondere die Möglichkeit, präoperativ gewonnene diagnostische Erkenntnisse zu vertiefen und zu erweitern und daraus sofort therapeutische Konsequenzen zu ziehen, hat zu einer stetigen Zunahme der so behandelten Gelenke geführt. Die grundsätzliche Möglichkeit, Ellenbogen und Sprunggelenk mit einem Arthroskop zu untersuchen, wurde bereits in den 30er-Jahren des letzten Jahrhunderts erkannt. Der enge und teilweise schwer einsehbare Gelenkraum verhinderte lange Zeit, dass die Arthroskopie dieser beiden Gelenke über das experimentelle Stadium hinauskam. Die Entwicklung kleinerer optischer Systeme und entsprechender Mikroinstrumente ermöglichte dann ab den 70er-Jahren zunächst die mehr diagnostisch geprägte Arthroskopie des Sprunggelenks und dann in zunehmendem Maße auch des Ellenbogengelenks, um dann rasch gewaltige Fortschritte zu machen. Heute ist die Arthroskopie des oberen Sprunggelenks eine Standardtherapie mit einem umfangreichen Indikationsspektrum. Ähnliches gilt für die Arthroskopie des Ellenbogengelenks. Wobei in absoluten Zahlen betrachtet die Ellenbogenarthro skopie immer noch deutlich hinter der Sprunggelenksarthroskopie zurückbleibt. Arthroscopy of the Elbow and Ankle

Conventionally, mesenchymal stem cells (MSC) are generated by plating cells from bone marrow (BM) or other sources into culture flasks and selecting plastic-adherent cells with fibroblastoid morphology. These cells express CD9, CD10, CD13, CD73, CD105, CD166, and other markers but show only a weak or no expression of the embryonic markers stage-specific embryonic antigen-4 (SSEA-4), Oct-4 and nanog-3. Using a novel protocol we prepared MSC from BM and non-amniotic placenta (PL) by culture of Ficoll-selected cells in gelatin-coated flasks in the presence of a serum-free, basic fibroblast growth factor (b-FGF)-containing medium that was originally designed for the expansion of human embryonic stem cells (ESC). MSC generated in gelatin-coated flasks in the presence of ESC medium revealed a four-to fivefold higher proliferation rate than conventionally prepared MSC which were grown in uncoated flasks in serum-containing medium. In contrast, the colony forming unit fibroblast number was only 1.5- to twofold increased in PL-MSC and not affected in BM-MSC. PL-MSC grown in ESC medium showed an increased surface expression of SSEA-4 and frizzled-9 (FZD-9), an increased Oct-4 and nestin mRNA expression, and an induced expression of nanog-3. BM-MSC showed an induced expression of FZD-9, nanog-3, and Oct-4. In contrast to PL-MSC, only BM-MSC expressed the MSC-specific W8B2 antigen. When cultured under appropriate conditions, these MSC gave rise to functional adipocytes and osteoblast-like cells (mesoderm), glucagon and insulin expressing pancreatic-like cells (endoderm), as well as cells expressing the neuronal markers neuron-specific enolase, glutamic acid decarboxylase-67 (GAD), or class III beta-tubulin, and the astrocyte marker glial fibrillary acidic protein (ectoderm). In conclusion, using a novel protocol we demonstrate that adult BM-and neonatal PL-derived MSC can be induced to express high levels of FZD-9, Oct-4, nanog-3, and nestin and are able of multi-lineage differentiation.

Aufgrund seines besonderen Aufbaus fehlt dem Knorpelüberzug der Gelenkflächen im Falle eines verletzungs -oder erkrankungsbedingten Defekts eine ausreichende Fähigkeit zur Selbstheilung. Da bei ausbleibender Heilung eines primär entstandenen Knorpelschadens, das sekundäre Arthroserisiko mit der Defektgröße erheblich zunimmt, ist gerade bei größeren Knorpelschäden, bestehender Symptomatik und speziell beim jüngeren Patienten die zügige Defektsanierung angezeigt. Für die biologische Rekonstruktion von Knorpelschäden des Kniegelenks stehen heutzutage verschiedene operative Verfahren zur Verfügung. In zahlreichen tierexperimentellen und klinischen Studien konnten Differenzialindikation und Wertigkeit der einzelnen Methoden gegeneinander abgewogen und Empfehlungen zu einer individuell angepassten Vorgehensweise formuliert werden. Neben der Regeneration des zerstörten Knorpelgewebes ist die zeitgleiche Sanierung allfälliger Achsabweichungen, Meniskusschäden und/oder Bandinstabilitäten für die Wiederherstellung der Gelenkfunktion und für die weitere Prognose wichtig. Unter Berücksichtigung geeigneter Indikationskriterien sind die Ergebnisse der Knorpelzelltransplantation auch nach längeren Verlaufszeiten viel versprechend, wobei sich diese Methode auch für Defekte mit einer Größe von mehr als 4 cm2 Flächenausdehnung eignet, bei denen andere Verfahren mit biologisch rekonstruktiver Zielsetzung meist überfordert sind. Neue Ansätze und Weiterentwicklungen bestehender Methoden zur Knorpelregeneration befinden sich derzeit in der Phase experimenteller und klinischer Erprobung.

ZusammenfassungIn tierexperimentellen und klinischen Studien konnte gezeigt werden, dass die zeitnahe biologische Rekonstruktion lokalisiert vollschichtiger Knorpelschäden des Kniegelenks der konservativen Behandlung oder der zu einem späteren Zeitpunkt durchgeführten biologischen Rekonstruktion überlegen ist. Dieser Zusammenhang wurde sowohl für die eigentliche Defektausheilung als auch für die Prävention von sekundär degenerativen Knorpelveränderungen gefun-den. Die frühzeitige Defektsanierung, insbesondere von größeren und klinisch symptomatischen Knorpeldefekten, ist daher nicht nur aus therapeutischer, sondern auch aus sozioökonomischer Sicht sinnvoll und wichtig. Für die bio-logische Rekonstruktion artikulärer Knorpeldefekte stehen mittlerweile eine Reihe verschiedener Verfahren zur Verfügung. Das geeignete Indikationsspektrum, Technik, Vorund Nachteile sowie die mittel- bis langfristigen Ergebnisse der verschiedenen Methoden werden in der vorliegenden Übersichtsarbeit vorgestellt.