State Of Extracellular Matrix Research Articles

Linking epileptic phenotypes and neural extracellular matrix remodeling signatures in mouse models of epilepsy

Epilepsies are multifaceted neurological disorders characterized by abnormal brain activity, e.g. caused by imbalanced synaptic excitation and inhibition. The neural extracellular matrix (ECM) is dynamically modulated by physiological and pathophysiological activity and critically involved in controlling the brain's excitability. We used different epilepsy models, i.e. mice lacking the presynaptic scaffolding protein Bassoon at excitatory, inhibitory or all synapse types as genetic models for rapidly generalizing early-onset epilepsy, and intra-hippocampal kainate injection, a model for acquired temporal lobe epilepsy, to study the relationship between epileptic seizures and ECM composition. Electroencephalogram recordings revealed Bassoon deletion at excitatory or inhibitory synapses having diverse effects on epilepsy-related phenotypes. While constitutive Bsn mutants and to a lesser extent GABAergic neuron-specific knockouts (BsnDlx5/6cKO) displayed severe epilepsy with more and stronger seizures than kainate-injected animals, mutants lacking Bassoon solely in excitatory forebrain neurons (BsnEmx1cKO) showed only mild impairments. By semiquantitative immunoblotting and immunohistochemistry we show model-specific patterns of neural ECM remodeling, and we also demonstrate significant upregulation of the ECM receptor CD44 in null and BsnDlx5/6cKO mutants. ECM-associated WFA-binding chondroitin sulfates were strongly augmented in seizure models. Strikingly, Brevican, Neurocan, Aggrecan and link proteins Hapln1 and Hapln4 levels reliably predicted seizure properties across models, suggesting a link between ECM state and epileptic phenotype.

AFM of tissue sections is a useful complementary tool as a biomedical marker

The aim of the study was to demonstrate a good diagnostic potential of atomic force microscopy (AFM) in tracking morphological changes in the extracellular matrix (ECM) of connective tissue due to pathological processes. Here we summarize our experience in AFM application in a number of biomedical studies on the connective tissue disease, both for research and clinical purposes. AFM has been shown to reveal visible deviations from the normal morphology of the extracellular matrix in diseased tissues. We found that AFM and related techniques are capable of tracking disease-related changes at different levels of collagen organization in the ECM. AFM may also monitor a ratio between collagen and non-fibrous material of the ECM, for example, in inflammatory and neoplastic processes. The FNS parameters provide quantification of the morphological changes visualized by AFM. The PeakForce QNM and nanoindentation studies give a further insight into the state of ECM via tracking changes in the local mechanical and adhesive properties. All our AFM studies appeared in a good agreement with the histological findings and generally had a superior sensitivity to the ECM pathological changes. AFM may serve as a valuable complementary diagnostic tool for tracking pathological changes in the connective tissue.

Alu insertion-deletion polymorphism of COL13A1 and LAMA2 genes: The analysis of association with longevity

The distribution of allele and genotype frequencies of Alu(I/D) polymorphic sites in the COL13A1 and LAMA2 genes coding extracellular matrix protein subunits was characterized in an ethnically homogeneous group (Tatars from the Republic of Bashkortostan, Russia). It was established that the frequency of individuals with the COL13A1*D/*D genotype was higher in the senile age period. The LAMA2*I/*D genotype was predisposing to longevity among women. According to the observed results, the frequency of the LAMA2*I/*D genotype was increased in senile individuals older than 90 years. The observed associations can be explained on the basis of the contemporary view by the importance of Alu elements in gene expression regulation at transcriptional and post-transcriptional levels, the involvement of collagen and laminin in maintaining the structure and function of the extracellular matrix, and the relationship between the extracellular matrix state, pathological changes and aging.

DIFFERENCES BETWEEN PROTEIN EXPRESSION AND EXTRACELLULAR MATRIX STATE ON UNIAXIAL STRETCHING FOR TENOGENIC DIFFERENTIATION

There have been no previous reports of tendon tissue engineering using mesenchymal stem cells (MSCs) with regard to quantitative evaluation of protein expression levels and observation of derived extracellular matrix (ECM) state. Therefore, we approached tendon tissue engineering from both perspectives. Human bone marrow MSCs (hBMSCs) were subjected to 8% or 10% cyclic stretching at 1 Hz to promote differentiation into tenocytes and ECM production. The type I collagen (Col I) and Tenascin-C (Tnc) protein expression levels were evaluated quantitatively by enzyme-linked immunosorbent assay (ELISA). Confocal fluorescence microscopy was employed to observe the derived ECM state. Col I state derived from 10%-stretched cells as ECM was elongated like actual tendon ECM, although the quantitative protein expression levels were slightly higher in 8%-stretched cells. The results suggested that the optimal uniaxial stretching ratio was different between protein expression levels and derived ECM state. Therefore, it is important to pay attention to both protein expression levels and ECM state in tendon tissue engineering.