Anatomical feature of knee joint in Aachen minipig as a novel miniature pig line for experimental research in orthopaedics.

BACKGROUND: The pig is a commonly used large animal model, since pigs share anatomical and physiological similarities with humans. In contrast to other experimental pig lines the Aachen minipig, as a robust novel minipig does not require housing with any barrier. To estimate transferability of results to human conditions, pig lines should be thoroughly characterized. PURPOSE: Therefore, we analyzed the anatomical pecularities of the knee joint of the novel "Aachen minipig" line raised for experimental conditions. METHODS: Eight knee joints of four adult Aachen minipigs were dissected measuring the dimensions of typical landmarks using a digital caliper. Hybrid pig and human knee joints served as controls. Cartilage of the Aachen minipig (trochlear groove, femoral condyles, menisci) were assessed histologically. RESULTS: The Aachen minipig shared its knee joint anatomy with the hybrid pig. In comparison to humans, peculiarities of the pig were demonstrated in the Aachen minipig: the lateral meniscus and the lateral tibial joint surface were significantly longer than the medial counterparts. The fibular head was covered by fibrocartilage and completely integrated into the lateral lower joint surface. The cartilage at the joint areas usually used for cartilage repair studies was in average 0.66±0.04mm thick. The porcine anterior cruciate ligament (ACL) attached with two bundles at the anterior tibial plateau separated from each other by the lateral anterior meniscotibial ligament. Aachen minipig articular and meniscal cartilage presented the typical histoarchitecture. CONCLUSIONS: The Aachen minipig reflects porcine anatomical peculiarities, which should be considered, especially for meniscus and ACL reconstruction.

Viscoelastic Behavior of Embroidered Scaffolds for ACL Tissue Engineering Made of PLA and P(LA-CL) After In Vitro Degradation.

A rupture of the anterior cruciate ligament (ACL) is the most common knee ligament injury. Current applied reconstruction methods have limitations in terms of graft availability and mechanical properties. A new approach could be the use of a tissue engineering construct that temporarily reflects the mechanical properties of native ligament tissues and acts as a carrier structure for cell seeding. In this study, embroidered scaffolds composed of polylactic acid (PLA) and poly(lactic-co-ε-caprolactone) (P(LA-CL)) threads were tested mechanically for their viscoelastic behavior under in vitro degradation. The relaxation behavior of both scaffold types (moco: mono-component scaffold made of PLA threads, bico: bi-component scaffold made of PLA and P(LA-CL) threads) was comparable to native lapine ACL. Most of the lapine ACL cells survived 32 days of cell culture and grew along the fibers. Cell vitality was comparable for moco and bico scaffolds. Lapine ACL cells were able to adhere to the polymer surfaces and spread along the threads throughout the scaffold. The mechanical behavior of degrading matrices with and without cells showed no significant differences. These results demonstrate the potential of embroidered scaffolds as an ACL tissue engineering approach.

Histological and biochemical characteristics of the rabbit anterior cruciate ligament in comparison to potential autografts.

Tissue engineering of an anterior cruciate ligament (ACL) implant with ACL cells requires detailed analysis of the tissue characteristics that should be mimicked. Therefore, we studied the histological and biochemical properties of rabbit derived ACLs in comparison to other knee-associated tendons that are used as autografts in men. Rabbit derived ACLs and Musculus (M.) semimembranosus, M. semitendinosus tendons and patellar ligaments were explanted from adult New Zealand white rabbits and analyzed histologically for tissue organization (e.g. cellularity, nuclear shapes, elastic fibers), total collagen and sulfated glycosaminoglycan (sGAG) contents. Gene expression analysis was performed for the main extracellular matrix (ECM) components type I collagen, decorin and the glycoprotein tenomodulin. The ACLs had a dimension of 1.39x0.39x0.1 cm in situ. They were characterized by high sGAG content in comparison to the other tendons/ligaments, whereas the total collagen content did not differ. ACLs possessed higher cellularity and lower feret diameter of the cell nuclei compared with the investigated rabbit-derived tendons. In ACLs long elastic fibers were observed. Concerning the gene expression level, lower transcription of tenomodulin was detected in the ACL compared with the other tendons, without significant difference in the decorin gene expression. The M. semitendinosus tendon had a significantly higher type I collagen expression than the ACL and the other investigated tendons. This phenotypical characterization of the lapine ACL presented in this study provides some key standards to evaluate tissue engineered ACL constructs to be tested in the rabbit model.

Effect of nasal sprays on an in vitro survival and morphology of nasoseptal cartilage.

Nasal sprays were introduced several years ago to support the treatment of allergic rhinitis. These sprays may come in direct contact with directly exposed nasoseptal cartilage (e.g. is case of nasoseptal perforation). To date, no studies investigated the effects of nasal sprays on cartilage tissues and cells. Therefore, our aim was to analyze the influence of two different nasal spray types (thixotropic and liposomal) on the vitality of nasoseptal chondrocytes. Human chondrocytes were isolated from surgically dissected tissues. Alternatively, nasal septa (porcine and human) tissue explants were used. The cell or explant cultures were treated with nasal sprays for 4-24 h. As a read-out, cell vitality and gene and protein expression profiles of type I and II collagen, SOX 9 and matrix metalloproteinase MMP-1 were compared to the untreated controls by means of real-time RT-PCR and immunostaining. Using the liposomal, but not thixotropic nasal spray in an explant or chondrocyte in vitro culture led to increased cell death, as compared to the untreated controls. A trend towards suppression of type II collagen and SOX 9 on protein level was found in cultures exposed to liposomal nasal spray, as compared to the controls. The thixotropic nasal spray has not affected the nasoseptal chondrocytes. Further studies with the use of viable nasoseptal cartilage explants and particularly using an in vivo animal model of exposed nasoseptal cartilage are necessary to clear the effect of liposomal spray on chondrocytes.