IntroductionCongenital muscular dystrophies (CMD) are a clinically and genetically heterogeneous group of neuromuscular disorders characterized by muscle weakness within the first two years of life. Collagen VI-related muscle disorders have recently emerged as one of the most common types of CMD. COL6 CMD is caused by deficiency and/or dysfunction of extracellular matrix (ECM) protein collagen VI. Currently, there is no specific treatment for this disabling and life-threatening disease. The primary cellular targets for collagen VI CMD therapy are fibroblasts in muscle, tendon and skin, as opposed to muscle cells for other types of muscular dystrophies. However, recent advances in stem cell research have raised the possibility that use of adult stem cells may provide dramatic new therapies for treatment of COL6 CMD.MethodsHere, we developed a procedure for isolation of human stem cells from the adipose layer of neonatal skin. The adipose-derived stem cells (ADSC) were examined for expression of ECM and related genes using gene expression array analysis. The therapeutic potential of ADSC was assessed after a single intramuscular transplantation in collagen VI-deficient mice.ResultsAnalysis of primary cultures confirmed that established ADSC represent a morphologically homogenous population with phenotypic and functional features of adult mesenchymal stem cells. A comprehensive gene expression analysis showed that ADSC express a vast array of ECM genes. Importantly, it was observed that ADSC synthesize and secrete all three collagen VI chains, suggesting suitability of ADSC for COL6 CMD treatment. Furthermore, we have found that a single intramuscular transplantation of ADSC into Col6a1−/−Rag1−/− mice under physiological and cardiotoxin-induced injury/regeneration conditions results in efficient engraftment and migration of stem cells within the skeletal muscle. Importantly, we showed that ADSC can survive long-term and continuously secrete the therapeutic collagen VI protein missing in the mutant mice.ConclusionsOverall, our findings suggest that stem cell therapy can potentially provide a new avenue for the treatment of COL6 CMD and other muscular disorders and injuries.

Background: Mutations in fibulin-4 cause autosomal recessive cutis laxa 1B, characterized by loose skin with vascular, lung, and skeletal abnormalities. Results: A mouse strain carrying a recurrent fibulin-4 missense mutation was generated and characterized. Conclusion: Mutant mice recapitulate the complete clinical features of the disease. Significance: The study provides the first evidence that fibulin-4 regulates collagen fibrillogenesis.

Background aims The adult stem cells produce a plethora of extracellular matrix (ECM) molecules and have a high potential as cell-based therapeutics for connective tissue disorders of the skin. However, the primary challenge of the stem cell-based approach is associated with the inefficient homing of systemically infused stem cells to the skin. Methods We examined chemotactic mechanisms that govern directional migration of the mesenchymal stem cells (MSCs) into the skin by conducting a comprehensive expression analysis of chemotactic molecules in MSCs and defined cutaneous tissues from normal and hereditary epidermolysis bullosa (EB)-affected skin. Results Analysis of chemokine receptors in short and long-term MSC cultures showed tissue culture-dependent expression of several receptors. Assessment of epidermis- and dermis-derived chemokines showed that majority of skin-originated chemotactic signals preferentially recruit different sets of leukocytes rather than MSCs. Analysis of the chemotactic molecules derived from EB-affected non-blistered skin showed only minor changes in expression of selected chemokines and receptors. Nevertheless, the data allowed us to define Ccl27-Ccr10 chemotactic axis as the most potent for the recruitment of MSCs to the skin. Our in vivo analysis demonstrated that uniform expression of Ccr10 on MSCs and alteration of Ccl27 level in the skin enhance extravasation of stem cells from circulation and facilitate their migration within cutaneous tissue. Conclusions Collectively, our study provides a comprehensive analysis of chemotactic signal in normal and EB-affected skin and proof-of-concept data demonstrating that alteration of the chemotactic pathways can enhance skin homing of the therapeutic stem cells.

BackgroundDystrophic epidermolysis bullosa (DEB), a rare genodermatosis, is characterized by the formation of intra-epidermal blistering and the development of chronic nonhealing skin wounds. Recently, attempts have been made to develop cell-based therapies for this currently intractable disorder. The molecular mechanisms that govern directional migration of the adult stem cells, allowing their efficient and controlled homing to the skin affected with DEB, are poorly understood. The key mechanism that regulates recruitment of leukocytes and progenitor stem cells to distal anatomical tissues affected with disease is chemotaxis, which depends on the signaling molecules, chemokines, and acts primarily as part of the host defense and repair mechanism.MethodsComprehensive proteomic screening of chemokines in the blister fluids of DEB-affected mice was conducted to define the inflammatory and immune activities, thus providing potential to examine local biological mechanisms and define the protein signature within lesional skin as a potential marker of disease activity. Also, the therapeutic relevance of identified chemotactic pathways was investigated in vivo, providing a basis for future clinical investigations.ResultsAssessment of blister fluid-derived chemokines showed a persistent presence of several chemotactic molecules, including CXCL1 + 2 and CXCL5. The majority of blister-originated chemotactic signals were associated with preferential recruitment of CD45+CXCR2+ and CD11b+CXCR2+ leukocytes. Systemic transplantation of an enriched CXCR2 population of mouse adipose-derived stem cells (mADSC) into DEB-affected mice demonstrated effective recruitment of cells to the blistering skin under the influence of blister-derived ligands and deposition of therapeutic type VII collagen.ConclusionsCollectively, these studies demonstrate that recruitment of mADSC into DEB skin is tightly controlled by disease-site chemotactic activities and suggest a potential mechanism for effective application of therapeutic stem cells for DEB.

Hairless mice were first described over 150 years ago in the form of the severe rhino mouse mutation (Hr rh) closely followed by a more mild phenotypic allele named hairless (Hr hr). Eventually both these alleles were established in both inbred and outbred mouse colonies. About 30 years ago these mice, primarily the hairless allele as it was called with the milder phenotype, became commonly used for skin cancer research, both UV light and chemical carcinogen induced, as the mice lacked hair as adults and were considered by many to be useful models of normal human skin. Subsequently, it was found that the Hr was a good model of papular atrichia. Today, there is a rich, but possibly confusing, landscape of different mutant Hr alleles present on a multitude of inbred, outbred, congenic, and segregating mouse strains. To confound this problem further there are also a number of mutant Hr phenocopies, i.e. mouse strains with mutations in genes that mimic the hairless phenotype, such as mutant alleles in the Vdr, Odc1, and other genes in the putrescine pathway. In this overview, we will clarify the phenotypes, genotypes, and mouse strain considerations that need to be accounted for when designing a study and interpreting the results of studies using these mice including many new alleles, both spontaneous and genetically engineered.