Richard Birk

Evaluation of the effects of different culture media on the myogenic differentiation potential of adipose tissue- or bone marrow-derived human mesenchymal stem cells

The creation of functional muscles/muscle tissue from human stem cells is a major goal of skeletal muscle tissue engineering. Mesenchymal stem cells (MSCs) from fat/adipose tissue (AT-MSCs), as well as bone marrow (BM-MSCs) have been shown to bear myogenic potential, which makes them candidate stem cells for skeletal muscle tissue engineering applications. The aim of this study was to analyse the myogenic differentiation potential of human AT-MSCs and BM-MSCs cultured in six different cell culture media containing different mixtures of growth factors. The following cell culture media were used in our experiments: mesenchymal stem cell growth medium (MSCGM)™ as growth medium, MSCGM + 5-azacytidine (5-Aza), skeletal muscle myoblast cell growth medium (SkGM)-2 BulletKit™, and 5, 30 and 50% conditioned cell culture media, i.e., supernatant of human satellite cell cultures after three days in cell culture mixed with MSCGM. Following the incubation of human AT-MSCs or BM-MSCs for 0, 4, 8, 11, 16 or 21 days with each of the cell culture media, cell proliferation was measured using the alamarBlue® assay. Myogenic differentiation was evaluated by quantitative gene expression analyses, using quantitative RT-PCR (qRT-PCR) and immunocytochemical staining (ICC), using well-defined skeletal markers, such as desmin (DES), myogenic factor 5 (MYF5), myosin, heavy chain 8, skeletal muscle, perinatal (MYH8), myosin, heavy chain 1, skeletal muscle, adult (MYH1) and skeletal muscle actin-α1 (ACTA1). The highest proliferation rates were observed in the AT-MSCs and BM-MSCs cultured with SkGM-2 BulletKit medium. The average proliferation rate was higher in the AT-MSCs than in the BM-MSCs, taking all six culture media into account. qRT-PCR revealed the expression levels of the myogenic markers, ACTA1, MYH1 and MYH8, in the AT-MSC cell cultures, but not in the BM-MSC cultures. The muscle-specific intermediate filament, DES, was only detected (by ICC) in the AT-MSCs, but not in the BM-MSCs. The strongest DES expression was observed using the 30% conditioned cell culture medium. The detection of myogenic markers using different cell culture media as stimuli was only achieved in the AT-MSCs, but not in the BM-MSCs. The strongest myogenic differentiation, in terms of the markers examined, was induced by the 30% conditioned cell culture medium.

Evaluation of the effect of static magnetic fields combined with human hepatocyte growth factor on human satellite cell cultures

Tissue engineering is a promising research field, which aims to create new functional muscle tissue in vitro, by utilizing the myogenic differentiation potential of human stem cells. The objective of the present study was to determine the effect of static magnetic fields (SMF), combined with the use of the myogenic differentiation enhancing hepatocyte growth factor (HGF), on human satellite cell cultures, which are one of the preferred stem cell sources in skeletal muscle tissue engineering. We performed almarBlue® proliferation assays and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) for the following myogenic markers: desmin (DES), myogenic factor 5 (MYF5), myogenic differentiation antigen 1 (MYOD1), myogenin (MYOG), myosin heavy chain (MYH) and α1 actin (ACTA1) to detect the effects on myogenic maturation. Additionally, immunohistochemical staining (ICC) and fusion index (FI) determination as independent markers of differentiation were performed on satellite cell cultures stimulated with HGF and HGF + SMF with an intensity of 80 mT. ICC verified the muscle phenotype at all time points. SMF enhanced the proliferation of satellite cell cultures treated with HGF. RT-PCR analysis, ICC and FI calculation revealed the effects of HGF/SMF on the investigated differentiation markers and stimulation with HGF and SMF verified the continuing maturation, however no significant increase in analysed markers could be detected when compared with control cultures treated with serum cessation. In conclusion, HGF or HGF + SMF stimulation of human satellite cell cultures did not lead to the desired enhancement of myogenic maturation of human satellite cell cultures compared with cell cultures stimulated with growth factor reduction.

Isoliert hochfrequente vestibuläre Läsion bei Patienten mit chronischen Schwindelbeschwerden

In the presented study video-head impulse test (vHIT) was performed in 72 patients with complaints of dizziness for more than 3 months who did not show any pathology in rotatory chair testing or caloric test, in order to analyzed high frequency vestibular-ocular-reflex (VOR). Retrospective data analyzed of rotatory chair testing, caloric tests and vHIT results were accomplished in 72 patients. Gain, gain variance and the occurrence of catch-up saccades were measured. 10 patients (n=10; 13.8%) showed pathologic vHOR results with reduced gain. In the remaining 62 patients, a median gain of 0.85 when tested to the right respectively 0.87 when tested to the left side was assed. Especially in patients with normal results in rotatory chair testing and caloric testing, who complain of persistent dizziness and imbalance, high frequency hVOR should also be evaluated using vHIT in order to objectify and document an isolated high frequency hVOR lesion.

Effect of selective small molecule inhibitors on MMP-9 and VEGFR-1 expression in p16-positive and -negative squamous cell carcinoma

The identification of molecular targets in the therapy of human papilloma virus (HPV)-associated head and neck squamous cell carcinoma (HNSCC) is a primary aim of cancer research. Matrix metalloproteinase 9 (MMP-9) and vascular endothelial growth factor receptor (VEGFR) have important roles in the development of HNSCC. The tyrosine kinase inhibitors, nilotinib, dasatinib, erlotinib and gefitinib are well established in the targeted therapy of tumors other than HNSCC. The present study aimed to investigate the alteration of MMP-9 and VEGFR-1 expression patterns following treatment with these tyrosine kinase inhibitors in p16-positive and -negative squamous carcinoma cells. MMP-9 and VEGFR-1 expression was evaluated using an ELISA in HNSCC 11A, HNSCC 14C and p16-positive CERV196 tumor cell lines, following treatment with nilotinib, dasatinib, erlotinib and gefitinib. A statistically significant reduction in MMP-9 and VEGFR-1 expression was observed in the p16-negative HNSCC 11A cells following treatment with all inhibitors (P<0.05). VEGFR-1 expression was significantly increased in p16-positive SCC cells following treatment with nilotinib, dasatinib, erlotinib and gefitinib (P<0.05). The expression of MMP-9 and VEGFR-1 was significantly altered by treatment with nilotinib, dasatinib, erlotinib and gefitinib in vitro. The results of the present study are attributed to the efficacy of the tested drugs and present potential compensatory strategies of cancer cells to avoid the antiangiogenic properties of the tested tyrosine kinase inhibitors in vitro.

Mupirocin reduces ciliary beat frequency of human nasal epithelial cells

Mupirocin is used worldwide for topical treatment of infected skin lesions, impetigo, and especially for nasal decolonization of patients with carriage of Staphylococci, including methicillin-resistant Staphylococcus aureus. Nevertheless, data regarding the effects of mupirocin on the nasal mucosa, in particular on ciliary beat frequency (CBF), is lacking to date. We tested the CBF of ciliated nasal epithelial cells under the influence of Mupirocin–calcium dissolved in tert-butyl alcohol (TBA) containing media in different concentrations comparable to clinical use. Ringer’s lactate solution and TBA served as negative control. Cells were visualized with a phase contrast microscope, and the CBF was measured with the SAVA system’s region of interest method. Mupirocin–calcium dissolved in TBA led to a statistically significant time- and concentration-dependent decrease in CBF compared to the negative control. TBA addition without mupirocin also led to a significant decrease in CBF, although to a lesser extent than mupirocin/TBA. In conclusion, CBF of human nasal epithelia is significantly reduced by mupirocin–calcium-containing solutions in therapeutic concentrations. Due to our results in this study, mupirocin as a nasal decolonization agent should be used only with care, with a strictly set medical indication, and additional care measures should be considered.