The Delayed Presentation of Achilles Tendon Ruptures Is Associated With Marked Alterations in the Gene Expression of COL1A1, MMPs, TIMPs, and IL-6.

BACKGROUND: Both acute and chronic Achilles tendon ruptures are affected by alterations in the extracellular matrix during the healing process of the tendon. Yet, these alterations in gene expression patterns are not well characterized. PURPOSE: To characterize temporal and spatial differences in gene expression patterns after an Achilles tendon rupture and to evaluate if cells from chronic Achilles tendon ruptures have the same ability to form new tendon tissue (tendon constructs) as healthy tendon cells. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 35 patients with surgically treated Achilles tendon ruptures were included in the study and divided into 3 groups: acute (<4 weeks), short-term chronic (1-6 months), and long-term chronic (>6 months). Biopsy specimens were collected during surgical repair and were used to analyze the gene expression within the different groups and to compare mRNA levels in the proximal and distal tendon ends. A complementary in vitro experiment was performed to evaluate if cells from chronic Achilles tendon ruptures can form tendon constructs. RESULTS: The mRNA levels for COL1A1 and COL3A1 were significantly higher in the short-term chronic group compared with the acute group (P < .05). Both MMP-1 and MMP-13 had the highest mRNA levels in the acute group (P < .01) compared with the long-term chronic group, while MMP-2 had the highest mRNA level in the short-term chronic group. Significant differences between the proximal and distal tendon ends were only detected for the monocyte and macrophage marker CD163 (P < .05), which was more expressed proximally. Cells extracted from chronic Achilles tendon ruptures displayed a similar ability and effectiveness to form tendon constructs as healthy tendon cells. CONCLUSION: A high collagenase gene activity after an Achilles tendon rupture indicated possible rapid matrix degradation in the acute phase. Chronic ruptures appeared to initiate the healing process even before treatment, indicated by the higher expression of collagen in the short-term chronic group. Cells from chronic Achilles tendon ruptures also displayed an ability to form new tendon tissue in vitro. CLINICAL RELEVANCE: The study shows a rapid increase in collagenase gene expression, which could lead to matrix degradation that continues for months after an Achilles tendon rupture.

Cartilage Tissue Engineering by the 3D Bioprinting of iPS Cells in a Nanocellulose/Alginate Bioink.

Cartilage lesions can progress into secondary osteoarthritis and cause severe clinical problems in numerous patients. As a prospective treatment of such lesions, human-derived induced pluripotent stem cells (iPSCs) were shown to be 3D bioprinted into cartilage mimics using a nanofibrillated cellulose (NFC) composite bioink when co-printed with irradiated human chondrocytes. Two bioinks were investigated: NFC with alginate (NFC/A) or hyaluronic acid (NFC/HA). Low proliferation and phenotypic changes away from pluripotency were seen in the case of NFC/HA. However, in the case of the 3D-bioprinted NFC/A (60/40, dry weight % ratio) constructs, pluripotency was initially maintained, and after five weeks, hyaline-like cartilaginous tissue with collagen type II expression and lacking tumorigenic Oct4 expression was observed in 3D -bioprinted NFC/A (60/40, dry weight % relation) constructs. Moreover, a marked increase in cell number within the cartilaginous tissue was detected by 2-photon fluorescence microscopy, indicating the importance of high cell densities in the pursuit of achieving good survival after printing. We conclude that NFC/A bioink is suitable for bioprinting iPSCs to support cartilage production in co-cultures with irradiated chondrocytes.

Strategies for patient profiling in articular cartilage repair of the knee: a prospective cohort of patients treated by one experienced cartilage surgeon.

PURPOSE: The purpose of this study was to report on the clinical outcome of a large heterogenic cartilage repair population treated with the profiling strategies of one experienced cartilage surgeon to provide evidence based tools for treatment selection in a clinical environment. METHODS: A total of 216 patients were identified in this prospective single-surgeon study. For the primary and secondary treatment of smaller defects, microfracture (MF) was used. Hyalograft C was used for first and second line larger defects, while carbon-fiber rod and pad implantations were used as a salvage procedure. RESULTS: Three years after the initial procedure, the clinical improvement was excellent for MF and Hyalograft C (P < 0.001) and good for carbon-fiber procedures (P < 0.05). Hyalograft C patients with prior anterior cruciate ligament reconstruction had less clinical improvement (P < 0.05), while MF patients with prior cartilage repair were more likely to fail (Odds Ratio 20.5, P < 0.05). CONCLUSION: This is the first study that provides an assessment of the treatment strategies used by an experienced cartilage surgeon. A treatment algorithm for cartilage repair in a heterogenic population was created that based on the findings of this study could be implemented in a clinical environment. LEVEL OF EVIDENCE: Prospective clinical case series, Level IV.

Human adipose-derived stem cells contribute to chondrogenesis in coculture with human articular chondrocytes.

Adipose tissue is easily available and contains high numbers of stem cells that are capable for chondrogenic differentiation. We hypothesize that a partial substitution of chondrocytes with autologous adipose-derived stem cells (ASC) might be a possible strategy to reduce the number of chondrocytes needed in matrix-associated autologous chondrocyte transplantation. To lay the ground, in vitro coculture experiments were performed using human chondrocytes and human ASC. Chondrocytes were obtained from donors undergoing matrix-associated autologous chondrocyte transplantation. ASC were isolated from liposuction material. Chondrocytes and ASC were seeded either in fibrin (Tisseel; Baxter, Vienna, Austria) or collagen matrix (Tissue Fleece; Baxter, Unterschleissheim, Germany). RNA for quantitative reverse transcriptase (RT)-polymerase chain reaction was isolated after 2 weeks of culture in chondrogenic medium, and after 4 weeks samples were processed for histology. Related to the number of chondrocytes used, coculture with ASC led to strong increase in collagen type IX mRNA expression, which is an indicator for long-term stability of cartilage. Moderate upregulation was shown for SOX9, aggrecan, melanoma inhibitory activity, cartilage link protein 1, and cartilage oligomeric matrix protein mRNA. However, expression of collagen I and collagen II indicates the synthesis of fibrous tissue, which might be due to the use of dedifferentiated chondrocytes. Tisseel provided slightly better chondrogenic conditions than Tissue Fleece. These data support the possibility to take advantage of ASC in cartilage regeneration in conjunction with autologous chondrocytes.

Coculture of human embryonic stem cells and human articular chondrocytes results in significantly altered phenotype and improved chondrogenic differentiation.

Human embryonic stem (hES) cells have been suggested as a cell source for the repair of cartilage lesions. Here we studied how coculture with human articular chondrocytes affects the expansion potential, morphology, expression of surface markers, and differentiation abilities of hES cells, with special regard to chondrogenic differentiation. Undifferentiated hES cells were cocultured with irradiated neonatal or adult articular chondrocytes in high-density pellet mass cultures for 14 days. Cocultured hES cells were then expanded on plastic and their differentiation potential toward the adipogenic, osteogenic, and chondrogenic lineages was compared with that of undifferentiated hES cells. The expression of different surface markers was investigated using flow cytometry and teratoma formation was studied using injection of the cells under the kidney capsule. Our results demonstrate that although hES cells have to be grown on Matrigel, the cocultured hES cells could be massively expanded on plastic with a morphology and expression of surface markers similar to mesenchymal stem cells. Coculture further resulted in a more homogenous pellet and significantly increased cartilage matrix production, both in high-density pellet mass cultures and hyaluronan-based scaffolds. Moreover, cocultured cells formed colonies in agarose suspension culture, also demonstrating differentiation toward chondroprogenitor cells, whereas no colonies were detected in the hES cell cultures. Coculture further resulted in a significantly decreased osteogenic potential. No teratoma formation was detected. Our results confirm the potential of the culture microenvironment to influence hES cell morphology, expansion potential, and differentiation abilities over several population doublings.

Limitacion en la extension de la rodilla luego de la reconstruccion del ligamento cruzado anterior / Limitation of extention of the knee following anterior cruciate ligament reconstruction

Se presenta un paciente masculino de 29 años de edad, con una reconstruccion inicial satisfactoria del ligamento cruzado anterior. Al alta presentaba una rodilla estable, indolora y con arco completo de movilidad. Consulta 6 años despues, refiriendo limitacion y dolor durante la extension terminal, al examen fisico se constato un deficit de 5 por ciento en la extension. La RM mostro un nodulo de 1,3 cm. de espesor ubicada en la parte anterior del injerto. La artroscopia evidencio la presencia de una masa de tejido cicatrizal ubicado que actuaba como tope mecanico en la extension. Se realizo el debridamiento artroscopico de la misma, logrando la extension completa luego del acto operatorio. La anatomia patologica informo un nodulo fibrogranulomatoso compatible con sindrome del ciclope. El paciente presento buena evolucion con una rodilla indolora y movilidad completa. Los pacientes que consultan por limitacion en la extension de la rodilla en el postoperatorio alejado, deben ser estudiados en forma clinica y con imagenes radiograficas y de RM para diagnosticar esta patologia. Si se confirma este diagnostico de sindrome de ciclope, el debridamiento artroscopico es el tratamiento de eleccion

Integracion donante-receptor del ligamento cruzado anterior en aloinjertos osteoarticulares: estudio histologico y molecular / Anterior cruciate ligament donor-receptor integration in osteoarticular allografts

Los objetivos del trabajo fueron determinar en un modelo porcino los aspectos biologicos y estructurales de la integracion del ligamento cruzado anterior enaloinjertos de femur distal y evaluar la incorporacion del ADN de los fibroblastos del receptor sobre el tejido donante (resumen truncado)

Artrosis de cadera: errores técnicos en artroplastías de cadera operadas por médicos especialistas y residentes: estudio comparativo de radiografías posoperatorias

El entrenamiento en artroplastía de cadera forma parte de los programas de residencias médicas. El médico especialista debe cumplir con su función docente y brindar excelencia en los tratamientos que indica. El propósito de este trabajo es evaluar diferencias en radiografías posoperatorias de artroplastías de cadera realizadas por residentes y especialistas. Se seleccionaron 96 radiografías posoperatorias inmediatas de 44 artroplastías realizadas por especialistas y 52 efectuadas por residentes para determinar en cada una los siguientes parámetros: discrepancia en longitud de miembros, inclinación, cementación y orientación del cótilo, centro de rotación obtenido, alineación y cementado del tallo femoral, alambrado y contacto de los bordes de la osteotomía del trocánter mayor y presencia de falsa vía inadvertida o fractura del fémur. Las diferencias entre los grupos fueron estadísticamente significativas para la ubicación del centro de rotación y el cementado del tallo femoral. Se discuten los resultados con aportes de la bibliografía y las probables implicancias de los hallazgos para la sobrevida de la prótesis. A pesar de una estrecha vigilancia existen diferencias entre artroplastías de cadera realizadas por cirujanos en formación y especialistas. Recomendamos estudios similares en servicios con residentes para determinar las diferencias y orientar el proceso de entrenamiento