Objective. Knee osteoarthritis (OA) is a degenerative joint disorder characterized by cartilage, bone, and synovial tissue changes that lead to pain and functional impairment. Joint distraction is a treatment that provides long-term improvement in pain and function accompanied by cartilage repair, as evaluated indirectly by imaging studies and measurement of biochemical markers. The purpose of this study was to evaluate cartilage tissue repair directly by histologic and biochemical assessments after joint distraction treatment.Methods. In 27 dogs, OA was induced in the right knee joint (groove model; surgical damage to the femoral cartilage). After 10 weeks of OA development, the animals were randomized to 1 of 3 groups. Two groups were fitted with an external fixator, which they wore for a subsequent 10 weeks (one group with and one without joint distraction), and the third group had no external fixation (OA control group). Pain/function was studied by force plate analysis. Cartilage integrity and chondrocyte activity of the surgically untouched tibial plateaus were analyzed 25 weeks after removal of the fixator.Results. Changes in force plate analysis values between the different treatment groups were not conclusive. Features of OA were present in the OA control group, in contrast to the generally less severe damage after joint distraction. Those treated with joint distraction had lower macroscopic and histologic damage scores, higher proteoglycan content, better retention of newly formed proteoglycans, and less collagen damage. In the fixator group without distraction, similarly diminished joint damage was found, although it was less pronounced.Conclusion. Joint distraction as a treatment of experimentally induced OA results in cartilage repair activity, which corroborates the structural observations of cartilage repair indicated by surrogate markers in humans.

Sertoli cells isolated from the adult mouse and human testis resume proliferation in culture. After 20 days of culture in Dulbecco modified Eagle medium/Ham F12 (DMEM/F12) medium containing 5%% fetal calf serum, about 36%% of the mouse Sertoli cells, identified by their immunohistochemical staining for the Sertoli cell marker vimentin, incorporated bromodeoxyuridine (BrdU). The renewed proliferation was associated with a 70%% decrease in expression of the cell cycle inhibitor CDKN1B (P27(kip1)) and a 2-fold increase in the levels of the proliferation inducer ID2. In vivo, the balance between cell cycle inhibitors and inducers probably is such that the cells remain quiescent, whereas in culture the balance is disturbed such that Sertoli cells start to proliferate again. The renewed proliferative activity of Sertoli cells in culture was further confirmed by double staining for BrdU and the Sertoli cell marker clusterin (CLU), showing about 25%% of the CLU-positive Sertoli cells to be also positive for BrdU after 13 days of culture. Radiobiologically, Sertoli cells are also different from other quiescent somatic cells in the testis because they express several DNA repair proteins (XRCC1, PARP1, and others). Indeed, a comet assay on irradiated Sertoli cells revealed a 70%% reduction in tail length and tail moment at 20 h after irradiation. Hence, Sertoli cells repair DNA damage, whereas other quiescent somatic testicular cells do not. This repair may be accomplished by nonhomologous end joining via XRCC1 and PARP1. In conclusion, cell kinetic and radiobiological data indicate that Sertoli cells more resemble arrested proliferating cells than the classic postmitotic and terminally differentiated somatic cells that they have always been assumed to be.

Osteoarthritis is a highly prevalent disease, age being the main risk factor. The age-related accumulation of advancedglycation-endproducts (AGEs) adversely affects the mechanical and biochemical properties of cartilage. The hypothesis that accumulation of cartilage AGEs in combination with surgically induced damage predisposes to the development of osteoarthritis was tested in vivo in a canine model. To artificially increase cartilage AGEs, right knee joints of eight dogs were repeatedly injected with ribose/ threose (AGEd-joints). Left joints with vehicle alone served as control. Subsequently, minimal surgically applied cartilage damage was induced and loading restrained as much as possible. Thirty weeks after surgery, joint tissues of all dogs were analyzed for biochemical and histological features of OA. Cartilage pentosidine levels were $5-fold enhanced (p ¼ 0.001 vs. control-joints). On average, no statistically significant differences in joint degeneration were found between AGEd and control-joints. Enhanced cartilage pentosidine levels did correlate with less cartilage proteoglycan release (R ¼ À0.762 and R ¼ À0.810 for total and newly-formed proteoglycans, respectively; p ¼ 0.028 and 0.015 for both). The current data support the diminished cartilage turnover, but only a tendency towards enhanced cartilage damage in AGEd articular cartilage was observed. As such, elevated AGEs do not unambiguously accelerate the development of early canine OA upon minimal surgical damage. Keywords: osteoarthritis; non-enzymatic glycation; canine; pentosidine; proteoglycan Osteoarthritis (OA), with a high prevalence and increasing incidence due to the aging population, having a large impact on the patient's quality of life, is characterized by progressive cartilage damage, bone changes, and secondary synovial inflammation. 1 As yet, the pathogenesis of OA is largely unknown. Several factors have been reported to predispose to the development of OA, such as genetic background, overweight, joint laxity, and muscle weakness. 2 However, undisputedly, the most important risk factor for development of OA is age. 3 The incidence of OA increases strongly with age: >50% of the population over 60 years of age is affected. 4,5 However, there are still many uncertainties how age contributes to the onset and progression of OA. Age-related changes in the articular cartilage are suggested to play an important role in the susceptibility of cartilage to OA.One of the major age-related changes in articular cartilage is the spontaneous modification of proteins by non-enzymatic glycation resulting in the accumulation of advanced glycation endproducts (AGEs). Nonenzymatic glycation is a post-translational modification of proteins by reducing sugars. The spontaneous condensation of reducing sugars with free amino groups in lysine or arginine residues on proteins leads to the formation of AGEs. 6 Pentosidine, a fluorescent AGE formed between lysine and arginine residues, is frequently used as marker for AGEs. AGEs are formed in all pr...

Tumor drug distribution and concentration are important factors for effective tumor treatment. A promising method to enhance the distribution and the concentration of the drug in the tumor is to encapsulate the drug in a temperature sensitive liposome. The aim of this study was to investigate the tumor drug distribution after treatment with various injected doses of different liposomal formulations of doxorubicin, ThermoDox (temperature sensitive liposomes) and DOXIL (non-temperature sensitive liposomes), and free doxorubicin at macroscopic and microscopic levels. Only ThermoDox treatment was combined with hyperthermia. Experiments were performed in mice bearing a human fibrosarcoma. At low and intermediate doses, the largest growth delay was obtained with ThermoDox, and at the largest dose, the largest growth delay was obtained with DOXIL. On histology, tumor areas with increased doxorubicin concentration correlated with decreased cell proliferation, and substantial variations in doxorubicin heterogeneity were observed. ThermoDox treatment resulted in higher tissue drug levels than DOXIL and free doxorubicin for the same dose. A relation with the distance to the vasculature was shown, but vessel perfusion was not always sufficient to determine doxorubicin delivery. Our results indicate that tumor drug distribution is an important factor for effective tumor treatment and that its dependence on delivery formulation merits further systemic investigation.