What is the greatest regulatory challenge in the translation of biomaterials to the clinic?

Leaders in the field comment on what they perceive to be the greatest barriers to biomaterial translation.

Implantation of a porcine acellular dermal graft in a primate model of rotator cuff repair.

Background: Non-cross-linked xenogeneic extracellular matrix graft materials have typically elicited a hypersensitivity reaction when implanted into humans or other primates. The purpose of this study was to examine the histologic and immune response to a non-cross-linked porcine-derived dermal extracellular matrix graft processed to remove the α-gal epitope.

Materials And Methods: Eight African green monkeys were implanted with porcine acellular dermal matrix (Conexa Reconstructive Tissue Matrix; Tornier Inc, Edina, MN, USA) to repair and augment a partial excision defect of the supraspinatus tendon of the rotator cuff.

Massage therapy education online: student satisfaction and achievement, part I.

In recent years, providers of massage therapy education have, in growing numbers, started to use online technologies to support the learning processes of their students. Using a narrative review of the existing online learning literature, this paper aims to provide a solid pedagogical foundation for these early explorations. It identifies five key factors-instructional pedagogy, quality of instruction, interaction and communication, individual learner qualities, and the online interface-that contribute to student satisfaction and achievement in the online context.

Decorin is a novel antagonistic ligand of the Met receptor.

Decorin, a member of the small leucine-rich proteoglycan gene family, impedes tumor cell growth by down-regulating the epidermal growth factor receptor. Decorin has a complex binding repertoire, thus, we predicted that decorin would modulate the bioactivity of other tyrosine kinase receptors. We discovered that decorin binds directly and with high affinity (K(d) = approximately 1.

A porcine-derived acellular dermal scaffold that supports soft tissue regeneration: removal of terminal galactose-alpha-(1,3)-galactose and retention of matrix structure.

Sub-optimal clinical outcomes after implantation of animal-derived tissue matrices may be attributed to the nature of the processing of the material or to an immune response elicited in response to xenogeneic epitopes. The ability to produce a porcine-derived graft that retains the structural integrity of the extracellular matrix and minimizes potential antigenic response to galactose-alpha-(1,3)-galactose terminal disaccharide (alpha-Gal) may allow the scaffold to support regeneration of native tissue. Dermal tissue from wild-type (WT-porcine-derived acellular dermal matrix [PADM]) or Gal-deficient (Gal(-/-) PADM) pigs was processed to remove cells and DNA while preserving the structural integrity of the extracellular matrix.

Genetic evidence for the coordinated regulation of collagen fibrillogenesis in the cornea by decorin and biglycan.

Decorin and biglycan are class I small leucine-rich proteoglycans (SLRPs) involved in regulation of collagen fibril and matrix assembly. We hypothesize that tissue-specific matrix assembly, such as in the cornea, requires a coordinate regulation involving multiple SLRPs. To this end, we investigated the expression of decorin and biglycan in the cornea of mice deficient in either SLRP gene and in double-mutant mice.

An antimetastatic role for decorin in breast cancer.

Decorin, a member of the small leucine-rich proteoglycan gene family, down-regulates members of the ErbB receptor tyrosine kinase family and attenuates their signaling, leading to growth inhibition. We investigated the effects of decorin on the growth of ErbB2-overexpressing mammary carcinoma cells in comparison with AG879, an established ErbB2 kinase inhibitor. Cell proliferation and anchorage-independent growth assays showed that decorin was a potent inhibitor of breast cancer cell growth and a pro-apoptotic agent.

Host response to implanted porcine-derived biologic materials in a primate model of abdominal wall repair.

Three commercially available porcine-derived biologic meshes were implanted in an Old World primate abdominal wall resection repair model to compare biological outcome as a predictor of clinical efficacy. Tissues were explanted over a 6-month period and evaluated for gross pathology, wound healing strength, mesenchymal cellular repopulation, vascularity, and immune response. In vivo functional outcomes were correlated with in vitro profile for each material.

Host response to human acellular dermal matrix transplantation in a primate model of abdominal wall repair.

Commercially available human acellular dermal matrix (HADM), AlloDerm((R)), was implanted as an interpositional graft in the abdominal wall of adult vervet monkeys. Host response to implanted HADM was evaluated and compared with a human cellular dermal matrix (HCDM) and a primate acellular dermal matrix (PADM). Clinical acceptance of the acellular grafts (HADM and PADM) and graft remodeling were evidenced by fibroblast repopulation and neoangiogenesis.

Extracellular Wound Matrices:A Novel Regenerative Tissue Matrix (RTM) Technology for Connective Tissue Reconstruction.

The restoration of structure, function, and physiology to damaged or missing tissue through the use of a regenerative tissue matrix (RTM) leads to regenerative healing rather than reparative scarring. While many processes exist to transform biologic materials into an extracellular matrix (ECM), only those that maintain the required structural and biochemical properties necessary to capture the intrinsic regenerative abilities of the body are suitable to produce an RTM. Histological examination using differential staining with hematoxylin and eosin stain or Verhoeff von Geisen stain of human biopsies of RTM obtained from 2 different abdominal surgery patients taken at 8- and 12 months were consistent with RTM remodeling into fascia-like tissue.

Decorin modulates fibrin assembly and structure.

Emerging evidence indicates that fibrin clotting is regulated by different external factors. We demonstrated recently that decorin, a regulator of collagen fibrillogenesis and transforming growth factor-beta activity, binds to the D regions of fibrinogen (Dugan, T.A.

Decorin protein core inhibits in vivo cancer growth and metabolism by hindering epidermal growth factor receptor function and triggering apoptosis via caspase-3 activation.

Decorin is not only a regulator of matrix assembly but also a key signaling molecule that modulates the activity of tyrosine kinase receptors such as the epidermal growth factor receptor (EGFR). Decorin evokes protracted internalization of the EGFR via a caveolar-mediated endocytosis, which leads to EGFR degradation and attenuation of its signaling pathway. In this study, we tested if systemic delivery of decorin protein core would affect the biology of an orthotopic squamous carcinoma xenograft.

Biglycan regulates the expression and sarcolemmal localization of dystrobrevin, syntrophin, and nNOS.

The dystrophin-associated protein complex (DAPC) provides a linkage between the cytoskeleton and the extracellular matrix (ECM) and is also a scaffold for a host of signaling molecules. The constituents of the DAPC must be targeted to the sarcolemma in order to properly function. Biglycan is an ECM molecule that associates with the DAPC.

Decorin core protein secretion is regulated by N-linked oligosaccharide and glycosaminoglycan additions.

Expression of decorin using the vaccinia virus/T7 expression system resulted in secretion of two distinct glycoforms: a proteoglycan substituted with a single chondroitin sulfate chain and N-linked oligosaccharides and a core protein glycoform substituted with N-linked glycans but without a glycosaminoglycan chain. In this report, we have addressed two distinct questions. What is the rate-limiting step in glycosaminoglycan synthesis? Is glycosylation with either N-linked oligosaccharides or glycosaminoglycan required for secretion of decorin? N-terminal sequencing of the core protein glycoform, the addition of benzyl-beta-d-xyloside, and a UDP-xylose: core protein beta-d-xylosyltransferase activity assay show that xylosylation is a rate-limiting step in chondroitin sulfate biosynthesis.

Interactions of the extracellular matrix proteoglycans decorin and biglycan with C1q and collectins.

Decorin and biglycan are closely related abundant extracellular matrix proteoglycans that have been shown to bind to C1q. Given the overall structural similarities between C1q and mannose-binding lectin (MBL), the two key recognition molecules of the classical and the lectin complement pathways, respectively, we have examined functional consequences of the interaction of C1q and MBL with decorin and biglycan. Recombinant forms of human decorin and biglycan bound C1q via both collagen and globular domains and inhibited the classical pathway.

Decorin evokes protracted internalization and degradation of the epidermal growth factor receptor via caveolar endocytosis.

Decorin inhibits the epidermal growth factor receptor (EGFR) by down-regulating its tyrosine kinase activity, thereby blocking the growth of a variety of transformed cells and tumor xenografts. In this study we provide evidence that decorin directly binds to the EGFR causing its dimerization, internalization, and ultimately its degradation. Using various pharmacological agents to disrupt clathrin-dependent and -independent endocytosis, we demonstrate that decorin evokes a protracted internalization of the EGFR primarily via caveolar-mediated endocytosis.

N-linked keratan sulfate in the aggrecan interglobular domain potentiates aggrecanase activity.

Keratan sulfate is thought to influence the cleavage of aggrecan by metalloenzymes. We have therefore produced a recombinant substrate, substituted with keratan sulfate, suitable for the study of aggrecanolysis in vitro. Recombinant human G1-G2 was produced in primary bovine keratocytes using a vaccinia virus expression system.

Decorin prevents metastatic spreading of breast cancer.

Metastases in breast cancer are a vital concern in treatment, with epidermal growth factor receptor and ErbB2 strongly implicated in mediating tumor invasion and spreading. In this study, we investigated the role of decorin in suppressing both primary breast carcinomas and pulmonary metastases. We show that decorin causes marked growth suppression both in vitro and in vivo using a metastatic breast cancer cell line and an orthotopic mammary carcinoma model.

Biologically active decorin is a monomer in solution.

It has been reported that decorin and its protein core can have molecular masses nearly double the size of those previously published, suggesting a dimeric structure. In this study we tested whether biologically active decorin and its glycoprotein core would form dimers in solution. We used homo- and hetero-bifunctional chemical cross-linking reagents, BS3 and sulfo-SMPB, respectively, as well as glutaraldehyde and found no preferential dimer formation, whether chemical cross-linking was performed in the presence or absence of live cells.

Decorin binds fibrinogen in a Zn2+-dependent interaction.

We have previously shown that decorin, a member of the small leucine-rich proteoglycan family of extracellular matrix proteoglycans/glycoproteins is a Zn(2+) metalloprotein at physiological Zn(2+) concentrations (Yang, V. W-C., LaBrenz, S.