Zeitschrift für Gewebewissenschaft und -technik

Autologous chondrocyte transplantation is a promising option for the repair of isolated osteoarthritic cartilage lesions that requires isolation and expansion of chondrocytes from a small cartilage biopsy prior to implantation. However, when cultured in vitro, chondrocytes lose their stable phenotype and dedifferentiate to fibroblastic-like cells. The study investigated the potential of pentosan polysulfate (PPS) sodium to restore the phenotype of dedifferentiated monolayer articular chondrocytes. Canine articular chondrocytes isolated from four cartilage samples were culture expanded to establish primary culture. First passage chondrocytes were cultured as alginate beads for 18 days under normoxia in PPS concentrations of 0, 1, 5, 15 and 40 μg/mL in 20% DMEM. Effect of PPS on type I, II and X collagen, aggrecan and Runx2 gene expression were evaluated by real-time PCR. Runx2, HIF-1α and HIF-2α protein expression were evaluated by Western blot and proteoglycan deposition was determined by Alcian blue stain. Dedifferentiated chondrocytes fully retained their phenotype as evidenced by increased synthesis of cartilage-specific genes, type II collagen and aggrecan mRNA with complete suppression of type I and X collagen at PPS concentrations of 15 and 40 μg/mL. Compared to the control, type II collagen and aggrecan mRNA were significantly upregulated (P<0.05) at 5, 15 and 40 μg/mL and 5 and 15 μg/mL PPS, respectively. PPS significantly enhanced proteoglycan with peak deposition at 5 μg/mL compared to control. HIF-1α and HIF-2α proteins were detectable at protein level for the first time under normoxia condition in alginate culture. The study demonstrates for the first time the restoration of dedifferentiated canine articular chondrocytes phenotype by combining alginate encapsulation with culture in PPS without the addition of known chondrocytic growth factors. The study confirms PPS as novel chondroinductive factor with potential to offer a solution to the major challenges that exist in cartilage tissue engineering.

A new composition of platelet-fibrin glue (FPG), gelatin (Gel), nanohydroxyapatite (nHA), silver nanoparticles (SNPs) and gold nanoparticles (GNPs) was synthesized and employed in preparation of hybrid scaffolds and was applied in bone tissue engineering in the surgically critical-sized bone defect in a rat model. Sixty bilateral radial bone defects were randomly divided into six groups including untreated defects, autograft and those treated with Gel/FPG/nHA containing scaffolds including nHA alone, nHA/SNPs, nHA/GNPs and nHA/SNPs/GNPs (n=10 in each group). The defects were assessed by radiography, histopathology, scanning electron microscopy and biomechanical testing. In comparison with the untreated defects, all the treated defects demonstrated significantly superior new bone formation, remodeling and bone tissue volume. Moreover, the defects treated with GNPs showed significantly higher ultimate strength, yield strength and stiffness. The nHA and nHA/SNPs moderately improved bone regeneration that were not close to the autograft in some parameters, whereas nHA/GNPs and nHA/SNPs/ GNPs significantly improved bone healing closely comparable with those of the autograft group in most parameters. In conclusion, although all the scaffolds had some beneficial effectiveness on bone regeneration, the scaffolds containing GNPs were more effective in improving the structural and functional properties of the newly formed bone and were more osteoinductive than other scaffolds and were comparable to the autograft. Therefore, the scaffolds including GNPs can be regarded as a promising option to be used in bone tissue engineering.

Breast ultrasound elastography allows acquiring a displacements estimation images that reflects the tissue elasticity of the area under ultrasound examination. The displacements analysis of the mammary tissues helps to provide an accurate diagnosis related to tissue stiffness evaluation. However; despite the fact that this imaging modality is promising and effective, it encounters a major problem, B-mode images are altered by speckle noise which comes from the difference in echogenicity of the imaged tissues, which deteriorates the diagnostic information, therefore, an application of displacements estimation methods on contaminated B-mode images, amplifies indirectly the speckle noise, causing a reduction of clinical evaluation capacity and prevention of rigorous clinical assessment. In this perspective, the development of tools for treating this problem is crucial and indispensable for controlling the appearance of speckle noise. In this paper, we propose a new strategy based on the bilinear deformable block matching (BDBM) technique, in order to improve the old bilinear deformable block matching (OBDBM) technique by improving the B-mode images pre-processing step, at this stage, the B-mode images processing before estimating displacements is sufficient to have a good estimate. The proposed approach does not only filter the image against noise, it also improves the estimation of tissue deformations, the developed approach is based on the coupling between the reconstruction by filtered back projection (FBP) technique with shrinkage wavelets. The proposed model was validated using in vivo database containing 20 B-mode images acquired before and after compression. The FBP approach was used to reconstruct the tissue texture, consequently improves the resolution and the contours erased by the noise, after that the shrinkage wavelets have been introduced to completely filter the image against speckle noise. By comparing our proposed method with OBDBM and monogenic techniques (displacement estimation method based monogenic technique), we show that it is the most efficient in term of standard deviation calculation between the pixels (SD), it is better also for calculating the contrast to noise ratio (CNR) and it provides an excellent structural similarity (SSIM). The results of the proposed technique are encouraging and it is ready to be used in mammary tissues displacements enhancement images for ultrasound elastography.