[Comparison of Bone Marrow Stromal Cells from Different Anatomical Locations for Evaluation of Their Suitability for Potential Clinical Applications]. / Porovnání stromálních bunek kostní drene z ruzných anatomických lokací z hlediska jejich mozného klinického vyuzití.

PURPOSE OF THE STUDY In patients older than 40 years of age, treatment of chondral lesions of the knee employing microfractures does not provide satisfactory outcomes. One of the contributing factors may be the age-related lack of sufficient mesenchymal stromal cells able to efficiently migrate into the desired site of the lesion. Concomitant application of mononuclear cells (MNCs) or cultured mesenchymal stem cells (MSCs) isolated from bone marrow and seeded on a 3D scaffold could provide an alternative enhancing therapeutic efficacy in these patients. The aim of our study was to assess two different sources of bone marrow for isolation of progenitor cells. To be specific, material obtained from proximal tibia and iliac crest (the commonly used bone marrow source) was compared in terms of quantity and quality of cells and their suitability for cellbased treatment of chondral lesions. MATERIAL AND METHODS Bone marrow was collected during a total knee replacement surgery from the iliac crest and the proximal metaphysis of the tibia from ten volunteers older than 40 years of age, using aspiration biopsy needles. The MNCs from the obtained material were isolated, cultured and analyzed for their phenotypic features. Both sources were compared as to the yield and viability of MNCs and MSCs as well as the ability of MSCs of chondrogenic differentiation. RESULTS The MNCs concentration/yield was significantly higher in samples from the iliac crests. Similar results were obtained with cultured MSCs after the first passage when the MSCs/MNCs ratio was compared. Nevertheless, the qualitative analysis that included MSCs immuno-phenotyping, viability and population doubling time showed no difference between the two tested bone marrow sources. DISCUSSION Particularly in older patients, therapies of chondral defects employing bone marrow-stimulating techniques result in unsatisfactory outcomes. Therefore, orthopedic surgeons have turned their attention to cell-based treatments. Bone marrow located in pelvic bone and metaphysis of long bones (distal femur, proximal tibia) contains mononuclear cells that possess features of MSCs. In accordance with other authors, quantitative differences between the cells from two anatomical locations were found in our cohort of patients. Qualitatively, however, there was no significant variability observed. We also confirmed that the metaphysis of proximal tibia is a suitable source for cultured MSCs. Moreover, in contrast to several reports, the quality of these cells does not appear to decrease with the patients age. CONCLUSIONS The iliac crest represents a superior bone marrow source for the MNCs and MSCs yield when compared with tibia. However, there was no qualitative difference between the isolated and cultured cells. The population doubling time analysis showed that the tibia is a good alternative source of MSCs which can be obtained at therapeutically relevant numbers for example for the treatment of chondral lesions of the knee. Key words: bone marrow, mesenchymal stem cells, MSC, mononuclear cells, chondral defects, osteoarthritis.

Absence of spinocerebellar ataxia type 3/Machado-Joseph disease within ataxic patients in the Czech population.

Although spinocerebellar ataxia type 3 (SCA3)/Machado-Joseph disease is the most common type of SCA worldwide, we did not identify any cases of the disease amongst SCA patients in the Czech population. It has been proposed that the prevalence of large normal alleles correlates with the frequency of various types of SCA. We have therefore attempted to resolve the absence of SCA3 in our population by investigating, within 204 normal chromosomes, the frequency and nature of CAG repeats as well as two intragenic polymorphisms. We found that large normal alleles with more than 33 CAG repeats were observed at a frequency of only 0.49%. Whereas most of the expanded alleles worldwide have the CA haplotype, this was the least common (5.4%) variant observed in our study, although it was associated with a larger mean CAG repeat length (26.9). We postulate that the absence of SCA3 in the Czech population might be explained by the lack of large normal alleles and consequently a relatively small reservoir for aberrant CAG expansions at the SCA3 locus.

Fluorescent multiplex PCR--fast method for autosomal dominant spinocerebellar ataxias screening.

Expansion of CAG trinucleotide repeats has been shown to cause a number of autosomal dominant spinocerebellar ataxias such as SCA1, SCA2, SCA3/MJD, SCA6 and SCA7. These disorders are characterized by a wide inter- and intrafamiliar variation in clinical features. The same mutation can result in different phenotypes and the very similar phenotypes can be caused by different mutations. Therefore it is necessary to investigate more SCA genes (according to prevalence) to identify the causal elongation. We developed a fast and efficient screening method based on touchdown multiplex PCR with fluorescent labelled primers for the most common types of SCAs (SCA 1, 2, 3 and 7). It has been reliable in 113 probands tested. Fragment analysis was performed by using 6% denaturing polyacrylamide gel and employing the automated DNA sequencer. This method considerably shortens the process of molecular genetic screening of SCAs and might be used as a tip for designing other SCA screening sets.

Can ataxin-2 be down-regulated by allele-specific de novo DNA methylation in SCA2 patients?

Spinocerebellar ataxia type 2 (SCA2) is caused by a CAG trinucleotide repeat expansion within the coding region of the ataxin-2 gene. Affected individuals typically have between 34 and 57 CAG repeats. Signs of the disorder generally begin in adulthood and include progressive ataxia, dysarthria, tremor, hyporeflexia, and slow saccades. As with other trinucleotide repeat disorders, SCA2 exhibits an inverse correlation between the size of the CAG repeat and the age at onset of clinically detectable disease, with neonatal cases of SCA2 being reported in individuals harboring over 200 CAG repeats. However, a wide range of age at onset is typically observed, especially in individuals with < 40 CAG repeats. CAG repeat number alone explains approximately 25-80% of the variability. In this paper, we hypothesize that the level of mutant ataxin-2 protein in affected cells contributes to these differences. One of the mechanisms that might influence this protein levels is de novo DNA methylation, which would specifically target the allele with the expanded CAG repeat leading to transcriptional silencing. Consequently, the symptoms of SCA2 would occur later in the patient's life history. Our postulations, as well as those previously reported to account for the phenotype of SCA2, are discussed.