Identification of ASAH1 as a susceptibility gene for familial keloids.

Keloids result from abnormal proliferative scar formation with scar tissue expanding beyond the margin of the original wound and are mostly found in individuals of sub-Saharan African descent. The etiology of keloids has not been resolved but previous studies suggest that keloids are a genetically heterogeneous disorder. Although possible candidate genes have been suggested by genome-wide association studies using common variants, by upregulation in keloids or their involvement in syndromes that include keloid formation, rare coding variants that contribute to susceptibility in non-syndromic keloid formation have not been previously identified.

Spatially controlled rhBMP-2 mediated calvarial bone formation in a transgenic mouse model.

The study aimed to investigate the localized osteogenic activity of recombinant human bone morphogenetic protein (rhBMP-2), when delivered using enzymatically crosslinkable injectable glycol chitosan hydrogel. A critical sized bilateral calvarial defect model was used wherein one defect was implanted with rhBMP-2 loaded hydrogel (HPP-GC+BMP). The neighboring defect was implanted with an osteoconductive, collagen hydroxyapatite matrix "Healos".

A Novel Epi-drug Therapy Based on the Suppression of BET Family Epigenetic Readers.

Recent progress in epigenetic research has made a profound influence on pharmacoepigenomics, one of the fastest growing disciplines promising to provide new epi-drugs for the treatment of a broad range of diseases. Histone acetylation is among the most essential chromatin modifications underlying the dynamics of transcriptional activation. The acetylated genomic regions recruit the BET (bromodomain and extra-terminal) family of bromodomains (BRDs), thereby serving as a molecular scaffold in establishing RNA polymerase II specificity.

Harnessing External Cues: Development and Evaluation of an In Vitro Culture System for Osteochondral Tissue Engineering.

Over the last decade, engineered structures have been developed for osteochondral (OC) tissue regeneration. While the optimal structure design is yet to be determined, these scaffolds require in vitro evaluation before clinical use. However, the means by which complex scaffolds, such as OC scaffolds, can be tested are limited.

Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia.

Gnathodiaphyseal dysplasia (GDD; MIM#166260) is an autosomal dominant syndrome with characteristic cemento-osseous lesions of jawbones, bone fragility, and diaphyseal sclerosis of tubular bones. To date, only five mutations in the proposed calcium-activated chloride channel ANO5/TMEM16E gene have been identified. In this study, we describe two families and two singular patients with three new mutations.

Deciphering the Epigenetic Code in Embryonic and Dental Pulp Stem Cells.

A close cooperation between chromatin states, transcriptional modulation, and epigenetic modifications is required for establishing appropriate regulatory circuits underlying self-renewal and differentiation of adult and embryonic stem cells. A growing body of research has established that the epigenome topology provides a structural framework for engaging genes in the non-random chromosomal interactions to orchestrate complex processes such as cell-matrix interactions, cell adhesion and cell migration during lineage commitment. Over the past few years, the functional dissection of the epigenetic landscape has become increasingly important for understanding gene expression dynamics in stem cells naturally found in most tissues.

Variable patterns of ectopic mineralization in Enpp1asj-2J mice, a model for generalized arterial calcification of infancy.

Generalized arterial calcification of infancy (GACI) is an autosomal recessive disorder characterized by early onset of extensive mineralization of the cardiovascular system. The classical forms of GACI are caused by mutations in the ENPP1 gene, encoding a membrane-bound pyrophosphatase/phosphodiesterase that hydrolyzes ATP to AMP and inorganic pyrophosphate. The asj-2J mouse harboring a spontaneous mutation in the Enpp1 gene has been characterized as a model for GACI.

Improving the permeability of lyophilized collagen-hydroxyapatite scaffolds for cell-based bone regeneration with a gelatin porogen.

Bone tissue engineering using biomaterial scaffolds and culture-expanded osteoprogenitor cells has been demonstrated in several studies; however, it is not yet a clinical reality. One challenge is the optimal design of scaffolds for cell delivery and the identification of scaffold parameters that can delineate success and failure in vivo. Motivated by a previous experiment in which a batch of lyophilized collagen-hydroxyapatite (HA) scaffolds displayed modest bone formation in vivo, despite having large pores and high porosity, we began to investigate the effect of scaffold permeability on bone formation.

FGF2 High Molecular Weight Isoforms Contribute to Osteoarthropathy in Male Mice.

Humans with X-linked hypophosphatemia (XLH) and Hyp mice, the murine homolog of the disease, develop severe osteoarthropathy and the precise factors that contribute to this joint degeneration remain largely unknown. Fibroblast growth factor 2 (FGF2) is a key regulatory growth factor in osteoarthritis. Although there are multiple FGF2 isoforms the potential involvement of specific FGF2 isoforms in joint degradation has not been investigated.

Genetics of aging bone.

With aging, the skeleton experiences a number of changes, which include reductions in mass and changes in matrix composition, leading to fragility and ultimately an increase of fracture risk. A number of aspects of bone physiology are controlled by genetic factors, including peak bone mass, bone shape, and composition; however, forward genetic studies in humans have largely concentrated on clinically available measures such as bone mineral density (BMD). Forward genetic studies in rodents have also heavily focused on BMD; however, investigations of direct measures of bone strength, size, and shape have also been conducted.

Generation of a mouse model for a conditional inactivation of Gtf2i allele.

The multifunctional transcription factor TFII-I encoded by the Gtf2i gene is expressed at the two-cell stage, inner cell mass, trophectoderm, and early gastrula stages of the mouse embryo. In embryonic stem cells, TFII-I colocalizes with bivalent domains and depletion of Gtf2i causes embryonic lethality, neural tube closure, and craniofacial defects. To gain insight into the function of TFII-I during late embryonic and postnatal stages, we have generated a conditional Gtf2i null allele by flanking exon 3 with loxP sites.

Epigenetic mechanisms involved in modulation of inflammatory diseases.

Purpose Of Review: The activation of inflammatory response is dependent upon genetic factors and epigenetic control mechanisms. This overview will highlight recent advances in the understanding of epigenetic dynamics during cellular inflammation.

Recent Findings: There is a growing body of evidence indicating that alterations of the chromatin state associate with an increased risk of chronic disease development and inflammation.

Ectopic mineralization of cartilage and collagen-rich tendons and ligaments in Enpp1asj-2J mice.

Generalized arterial calcification of infancy (GACI), an autosomal recessive disorder caused by mutations in the ENPP1 gene, manifests with extensive mineralization of the cardiovascular system. A spontaneous asj-2J mutant mouse has been characterized as a model for GACI. Previous studies focused on phenotypic characterization of skin and vascular tissues.

Evaluation of the donor cell contribution in rhBMP-2 mediated bone formation with chitosan thermogels using fluorescent protein reporter mice.

Our current understanding regarding the contribution of donor cells in growth factor and cell based tissue regeneration strategies is limited. The present study attempts to utilize fluorescent protein reporter mice [Col3.6Topaz (enhanced yellow fluorescent protein, EYFP) as host and Col3.

Regenerative biology of tendon: mechanisms for renewal and repair.

Understanding the molecular and cellular mechanisms underlying tissue turnover and repair are essential towards addressing pathologies in aging, injury and disease. Each tissue has distinct means of maintaining homeostasis and healing after injury. For some, resident stem cell populations mediate both of these processes.

Cell and matrix response of temporomandibular cartilage to mechanical loading.

Objectives: The generation of transgenic mice expressing green fluorescent proteins (GFPs) has greatly aided our understanding of the development of connective tissues such as bone and cartilage. Perturbation of a biological system such as the temporomandibular joint (TMJ) within its adaptive remodeling capacity is particularly useful in analyzing cellular lineage progression. The objectives of this study were to determine: (i) if GFP reporters expressed in the TMJ indicate the different stages of cell maturation in fibrocartilage and (ii) how mechanical loading affects cellular response in different regions of the cartilage.

Gdf5 progenitors give rise to fibrocartilage cells that mineralize via hedgehog signaling to form the zonal enthesis.

The sequence of events that leads to the formation of a functionally graded enthesis is not clearly defined. The current study demonstrates that clonal expansion of Gdf5 progenitors contributes to linear growth of the enthesis. Prior to mineralization, Col1+ cells in the enthesis appose Col2+ cells of the underlying primary cartilage.

Response of knee fibrocartilage to joint destabilization.

Objective: A major challenge to understanding osteoarthritis (OA) pathology is identifying the cellular events that precede the onset of cartilage damage. The objective of this study is to determine the effect of joint destabilization on early changes to fibrocartilage in the joint.

Design/methods: The anterior cruciate ligament was transected in collagen reporter mice (Col1CFP and ColXRFP).

Fixation stability dictates the differentiation pathway of periosteal progenitor cells in fracture repair.

This study compared fracture repair stabilized by intramedullary pin (IMP) or external fixation (EF) in GFP reporter mice. A modified IMP was used as control while EF utilized six needles inserted transversely through the tibia and into a segment of a syringe barrel. X-rays taken at days 0, 14, and 35 showed that IMP resulted in significant three-dimensional deformity with a large callus while EF showed minimal deformity and callus formation.

Effects of cell-attachment and extracellular matrix on bone formation in vivo in collagen-hydroxyapatite scaffolds.

Cell-based tissue engineering can be used to replace missing or damaged bone, but the optimal methods for delivering therapeutic cells to a bony defect have not yet been established. Using transgenic reporter cells as a donor source, two different collagen-hydroxyapatite (HA) scaffolds, and a critical-size calvarial defect model, we investigated the effect of a cell-attachment period prior to implantation, with or without an extracellular matrix-based seeding suspension, on cell engraftment and osteogenesis. When quantitatively compared, the in-house scaffold implanted immediately had a higher mean radiopacity than in-house scaffolds incubated overnight.

Mechanisms and models of endoplasmic reticulum stress in chondrodysplasia.

Chondrodysplasias are a group of genetic disorders that affect the development and growth of cartilage. These disorders can result in extreme short stature, craniofacial defects, joint malformation, and early osteoarthritis; severely impacting quality of life for affected individuals. Many chondrodysplasias are caused by mutations in genes encoding cartilage extracellular matrix (ECM) proteins.

Dental Anomalies Associated with Craniometaphyseal Dysplasia.

Craniometaphyseal dysplasia (CMD) is a rare genetic disorder encompassing hyperostosis of craniofacial bones and metaphyseal widening of tubular bones. Dental abnormalities are features of CMD that have been little discussed in the literature. We performed dentofacial examination of patients with CMD and evaluated consequences of orthodontic movement in a mouse model carrying a CMD knock-in (KI) mutation (Phe377del) in the Ank gene.

Dental abnormalities in a mouse model for craniometaphyseal dysplasia.

Mice carrying a knock-in mutation (Phe377del) in the Ank gene replicate many skeletal characteristics of human craniometaphyseal dysplasia, including hyperostotic mandibles. Ank (KI/KI) mice have normal morphology of erupted molars and incisors but excessive cementum deposition with increased numbers of Ibsp- and Dmp1-positive cells on root surfaces. The cervical loops of adult Ank (KI/KI) lower incisors are at the level of the third molars, while they are close to the mandibular foramen in Ank (+/+) mice.

Diversity and complexity in chromatin recognition by TFII-I transcription factors in pluripotent embryonic stem cells and embryonic tissues.

GTF2I and GTF2IRD1 encode a family of closely related transcription factors TFII-I and BEN critical in embryonic development. Both genes are deleted in Williams-Beuren syndrome, a complex genetic disorder associated with neurocognitive, craniofacial, dental and skeletal abnormalities. Although genome-wide promoter analysis has revealed the existence of multiple TFII-I binding sites in embryonic stem cells (ESCs), there was no correlation between TFII-I occupancy and gene expression.