Background/Aims: Autologous chondrocyte (CC) transplantation has the disadvantages of requiring two surgical interventions and in vitro expansion of cells, implying the risk of cellular dedifferentiation. Our clinical aim is to develop a one-step procedure for autologous CC transplantation, i.e. harvesting, isolation and reimplantation of CC performed in one single surgical procedure. Platelet-rich plasma (PRP) is a source of autologous growth factors reported to have mitogenic effects. The objective of this study was to test the influence of PRP as an autologous scaffold on freshly isolated CC and mesenchymal stem cells (MSC). Methods: CC and MSC were subjected to two- or three-dimensional (3D) growth systems, either with or without PRP. Chondrogenic differentiation was determined via quantification of collagen type II mRNA and immunohistochemical staining. Results: We observed a proliferative effect for MSCs exposed to PRP in monolayer culture and an increase in the expression of chondrogenic markers when cells are exposed to a 3D environment. CCs exposed to PRP show a decrease in the chondrogenic phenotype with increasing proliferative activity. Conclusion: PRP has a proliferative effect on CCs and MSCs. In a one-step procedure for autologous CC transplantation, this might be an advantage over other scaffold materials, but confirmation in in vivo studies is required.

The fracture of bone plays a key role in osteoporosis. BMD measurement, however, is only an indirect parameter of this phenomenon. We therefore developed a highly sensitive three-point bending test for the metaphyseal tibias in rats to evaluate stiffness and strength. This was validated in a right-left comparison and a bioassay with soy-free food, estradiol, raloxifene, and testosterone in orchidectomized rats.Introduction: Osteoporosis becomes manifest predominantly in the metaphyseal rat tibia. The antiosteoporotic character of substances should, therefore, be tested (mechanically) in this bone area. Materials and Methods:We evaluated a new three-point bending test for the metaphyseal tibia in rats in a right-left trial. In an animal experiment, we studied the change of bone quality under estradiol (E)-, raloxifene (R)-, and testosterone (T)-supplemented food and compared it with trabecular BMD (qCT). Results: In the right-left comparison, the mean difference between the metaphyseal loads of both tibias in 37 rats was 8.43% for the maximum load (F max ) and 6.46% for the failure load (fL). These results show the high reproducibility of the test, because they are close to the usual intraindividual difference of the two extremities. In a second experiment, four groups of 11 3-month-old male orchidectomized rats were fed with soy-free food only (C) or with the additives E, T, or R for 12 weeks. E and R were similar for F max and fL. There were significant differences in the stiffness (E ‫ס‬ 406.92 N/mm versus R ‫ס‬ 332.08 N/mm), the yield load (yL; E ‫ס‬ 99.17 N versus R ‫ס‬ 83.33 N), and the ratio between yL and F max (E ‫ס‬ 86.33% versus R ‫ס‬ 76.37%). T was similar to the controls concerning F max , fL, and stiffness. There were significant differences in yL (T ‫ס‬ 49.00N versus C ‫ס‬ 39.5N) and the ratio between yL and F max (T ‫ס‬ 64.28% versus C ‫ס‬ 51.28%). Conclusions: Estradiol is superior to raloxifene concerning stiffness and yield load, and both are superior to testosterone. We conclude that the described three-point bending test for the metaphyseal tibia is a highly sensitive method to study hormones and substances with regard to their osteoprotective character. The precision and the low SD of the presented results are superior to the data from qCT and the calculated index of stiffness (SSI).

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Wound healing is a complex biological process that requires a well-orchestrated interaction of mediators as well as resident and infiltrating cells. In this context, mesenchymal stem cells play a crucial role as they are attracted to the wound site and influence tissue regeneration by various mechanisms. In chronic wounds, these processes are disturbed. In a comparative approach, adipose-derived stem cells (ASC) were treated with acute and chronic wound fluids (AWF and CWF, respectively). Proliferation and migration were investigated using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and transwell migration assay. Gene expression changes were analysed using quantitative real time-polymerase chain reaction. AWF had a significantly stronger chemotactic impact on ASC than CWF (77·5% versus 59·8% migrated cells). While proliferation was stimulated by AWF up to 136·3%, CWF had a negative effect on proliferation over time (80·3%). Expression of b-FGF, vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 was strongly induced by CWF compared with a mild induction by AWF. These results give an insight into impaired ASC function in chronic wounds. The detected effect of CWF on proliferation and migration of ASC might be one reason for an insufficient healing process in chronic wounds.

Wound healing is a complex and dynamic process with different distinct and overlapping phases from homeostasis, inflammation and proliferation to remodelling. Monitoring the healing response of injured tissue is of high importance for basic research and clinical practice. In traditional application, biological markers characterize normal and abnormal wound healing. Understanding functional relationships of these biological processes is essential for developing new treatment strategies. However, most of the present techniques (in vitro or in vivo) include invasive microscopic or analytical tissue sampling. In the present study, a non-invasive alternative for monitoring processes during wound healing is introduced. Within this context, hyperspectral imaging (HSI) is an emerging and innovative non-invasive imaging technique with different opportunities in medical applications. HSI acquires the spectral reflectance of an object, depending on its biochemical and structural characteristics. An in-vitro 3-dimensional (3-D) wound model was established and incubated without and with acute and chronic wound fluid (AWF, CWF), respectively. Hyperspectral images of each individual specimen of this 3-D wound model were assessed at day 0/5/10 in vitro, and reflectance spectra were evaluated. For analysing the complex hyperspectral data, an efficient unsupervised approach for clustering massive hyperspectral data was designed, based on efficient hierarchical decomposition of spectral information according to archetypal data points. It represents, to the best of our knowledge, the first application of an advanced Data Mining approach in context of non-invasive analysis of wounds using hyperspectral imagery. By this, temporal and spatial pattern of hyperspectral clusters were determined within the tissue discs and among the different treatments. Results from non-invasive imaging were compared to the number of cells in the various clusters, assessed by Hematoxylin/Eosin (H/E) staining. It was possible to correlate cell quantity and spectral reflectance during wound closure in a 3-D wound model in vitro.