Tissue engineering of the anterior cruciate ligament-sodium dodecyl sulfate-acellularized and revitalized tendons are inferior to native tendons.

The acellularization of tendons using detergents (sodium dodecyl sulfate, Triton-X, tri-nitro-butyl-phosphate) is a new source of scaffolds for tissue engineering in anterior cruciate ligament (ACL) repair. In vitro testing demonstrated that acellular tendon scaffolds are biocompatible and show good biomechanical properties, but in vivo confirmation of these results is not yet available. Therefore, the aim of this study was to see in vivo if an acellular allogenic construct colonized with autologous fibroblasts improves the quality of ACL reconstruction. ACL replacement was performed in 31 New Zealand White rabbits using a standardized model. Fifteen animals received autologous semitendinosus tendon, whereas 16 animals were treated with a tissue-engineered construct. This construct was made by acellularization of allogenic semitendinosus tendons using sodium dodecyl sulfate and subsequent in vitro colonization with autologous fibroblasts. Eight weeks postoperatively, macroscopic, biomechanical (ultimate load to failure, elongation, stiffness; n = 8/9), and histological (n = 5) examinations were performed. Biomechanical testing showed decreasing strength of the constructs at 8 weeks after implantation compared with the direct postsurgical strength. However, tissue-engineered constructs (F = 19.7 +/- 20.3 N) were significantly weaker than autologous tendons (F = 61.2 +/- 31.2 N). Histologically, the autologous tendons showed signs of partial necrosis and tissue remodeling. The tissue-engineered constructs exhibited an inflammatory reaction and showed both repopulated and acellular regions. In conclusion, in vivo results were much more unfavorable than in vitro results had suggested. Further studies have to be performed to test if modifications of the acellularization process yield better results in vivo.

Do we need synthetic osteotomy augmentation materials for opening-wedge high tibial osteotomy.

High tibial osteotomy (HTO) is an increasing popular method to treat unicompartimental osteoarthritis of the knee in younger, active patients. In so doing one tries to delay the need for total or unicompartimental joint replacement. The augmentation of HTO opening gaps with supporting material is discussed controversially, especially after the introduction of locking plates, which contribute to the decline of the non-union rate. Currently, we do not recommend synthetic augmentation, when using locking plates in HTO with opening angles less than 10 degrees . In our recent randomized study we could histologically and radiologically demonstrate the complete rebuilding of lamelliform bone in patients without synthetic augmentation, whilst bony ingrowth into the hydroxyapatite/tricalcium phosphate (HA/TCP) wedge of augmented osteotomies just slowly progressed. In contrast to unaugmented osteotomies, there was no advantage in using HA/TCP wedges or the combination of HA/TCP wedges and platelet rich plasma (PRP) as supporting material after 12 months. In osteotomies where an opening angle bigger than 7.5 degrees is chosen, rigid locking plates should be used. In our opinion, autologous iliac crest graft should be used in the high-risk patients (obese, smoker, opening angle bigger than 10 degrees ). Whether synthetic augmentation combined with PRP is equal or even superior to autologous iliac crest graft in openings bigger than 10 degrees has not been proven yet.

Tissue engineering of the anterior cruciate ligament: a new method using acellularized tendon allografts and autologous fibroblasts.

INTRODUCTION: The availability of autogenous tendons (middle part of patellar tendon, semitendinosus/gracilis, or quadriceps tendon) for cruciate ligament reconstructions is restricted and related to withdrawal morbidity. Allografts and synthetic ligament materials often show problems regarding long-term stability and immunological reactions. Therefore, the aim of this study was to develop and characterize a new scaffold based on acellular allografts seeded with autologous cells for tissue engineering of the anterior cruciate ligament (ACL). MATERIALS AND METHODS: Semitendinosus tendons of New Zealand White (NZW) rabbits were harvested and acellularized using the detergent sodium dodecyle sulfate (SDS) as the main ingredient. After that, cultured (37 degrees C, 5% CO(2), medium) dermal fibroblasts were injected into the tendons. These constructs were further cultivated for 4, 7, or 14 days under the same culture conditions. Native, acellular, and seeded tendons underwent biomechanical testing (ultimate load to failure [N], stiffness [N/mm], and elongation [%], each n = 9] and histological hematoxylin-eosin (H.E.) staining. Detailed immunohistochemical (collagen I, III, IV, VI, pro-collagen I, versican, and vimentin) analyses were conducted to detect changes in the composition and structure of the extracellular matrix (ECM) after acellularization. RESULTS: Histologically, a cell-free, crimped slack tendon structure after acellularization and a good integration of the cells after injection (4, 7, and 14 days) were seen. Metabolic activity of the seeded cells was demonstrated by positive immunohistochemical staining for pro-collagen I, which was negative in nonseeded constructs. Major differences in staining patterns of the various other ECM components were not observed. Biomechanically, the maximum load to failure of these tendons was comparable to native tendons (P = 0.429; native 134.5 +/- 12.9 N; acellular 118.5 +/- 7.3 N; seeded 132.3 +/- 5.6 N). Stiffness and elongation were comparable between native and acellular tendons, but differed significantly after seeding (P < 0.001). CONCLUSION: The described method is suitable to make tendons completely cell free without changing their major biomechanical properties. Preservation of the ECM and of the collagen fiber structure by this method should give an ideal environment for autologous cell integration and metabolic activity in contrast to other approaches for tissue acellularization. The cell disruption and extraction of cell detritus should minimize adverse immunogenic reactions.

Encouraging early clinical experience with deliberately delayed temporary fetoscopic tracheal occlusion for the prenatal treatment of life-threatening right and left congenital diaphragmatic hernias.

OBJECTIVE: In order to assess the effect of deliberately delayed percutaneous fetoscopic tracheal occlusion on survival of fetuses with life-threatening congenital diaphragmatic hernia. METHODS: Eight fetuses with life-threatening congenital diaphragmatic hernia underwent fetoscopic tracheal balloon occlusion between 29 + 0 and 32 + 4 weeks of gestation. Delayed occlusion was chosen in order to minimize potentially negative pulmonary effects from premature delivery as a result of fetal surgery. In addition, we wanted to become able to provide all available postnatal intensive care treatment means in these patients. RESULTS: Six of the 8 fetuses survived to discharge from hospital. CONCLUSION: Delayed fetoscopic tracheal balloon occlusion may be rewarded with lung growth sufficient to allow survival of fetuses with life-threatening congenital diaphragmatic hernia.

Intra-amniotic multimodal fetal echocardiography in sheep: a novel imaging approach during fetoscopic interventions and for assessment of high-risk pregnancies in which conventional imaging methods fail.

During fetoscopic interventions, intraesophageal placement of intravascular ultrasound (US) catheters for fetal hemodynamic monitoring may result in esophageal injury in very small fetuses. Moreover, conventional fetal imaging by the transvaginal or transabdominal routes may be impossible in some high-risk pregnancies. The purpose of our study in sheep was to assess the potential of a phased-array intravascular US catheter for intra-amniotic fetal echocardiography. The catheter was percutaneously inserted into the amniotic cavity in seven pregnant ewes at between 78 to 98 days of gestation and permitted high-quality 2-D imaging of the fetal heart and multimodal Doppler assessment of fetal cardiovascular flows. Fetoscopic examination of intra-amniotic contents after intra-amniotic imaging was finished did not display any injury to intra-amniotic contents. The intra-amniotic imaging approach may provide an effective alternative in humans for monitoring during fetoscopic interventions, and to assess fetal anatomy and hemodynamics in high-risk pregnancies when sufficient images cannot be obtained by conventional routes.