Biomedical subjects

Jennifer Elisseeff

Publications and source records attributed to Jennifer Elisseeff.

9 recordsLinked to original sources

PubMed2006

Immobilized fibrinogen in PEG hydrogels does not improve chondrocyte-mediated matrix deposition in response to mechanical stimulation.

The present investigation aims to explore the role of cell-scaffold interactions and whole cell compression in chondrocyte mechanotransduction using encapsulating poly(ethylene glycol) (PEG) hydrogel scaffolds and primary bovine chondrocytes. Scaffolds made from PEG hydrogels with immobilized fibrinogen molecules were seeded with chondrocytes and subjected to 15% dynamic compressive strain at 1-Hz frequency. Dynamic strain stimulation resulted in a 37% increase in the levels of sulfated glycosaminoglycan (sGAG) after 2 weeks of stimulation, when compared to static controls. Comparing results of the PEG-fibrinogen scaffolds with their respective PEG control group did not show significant differences between the two, even following 2 weeks of dynamic mechanical stimulation. Accordingly, these findings indicate that while cell deformations cause metabolic changes in chondrocytes seeded in PEG hydrogels, it is difficult to ascertain the role of matrix bioactivity in enhancing chondrocyte mechanotransduction in encapsulating scaffolds subjected to physical deformations. This study shows how interactions between mechanical stimulation and scaffold composition are evaluated using an experimental approach and customized biomaterial scaffolds.

Animals↗

PubMed2006

Enhanced chondrogenic differentiation of murine embryonic stem cells in hydrogels with glucosamine.

Differentiation of embryonic stem (ES) cells generally occurs after formation of three-dimensional cell aggregates, known as embryoid bodies (EBs). We have previously reported that hydrogels provide EBs a supportive environment for in vitro chondrogenic differentiation and three dimensional tissue formation [Hwang NS, et al. The Effects of three dimensional culture and growth factors on the chondrogenic differentiation of murine ES cells. Stem Cells 2006;24:284-91]. In this study, we report chondrogenic differentiation of murine ES cells encapsulated in photopolymerizing poly(ethylene-glycol)-based (PEG) hydrogels in the presence of glucosamine (GlcN), an amino monosaccharide found in chitin, glycoproteins and glycosaminoglycans such as hyaluronic acid, chondroitin sulfate and heparin sulfate. We examined the growth and differentiation of encapsulated EBs in standard chondrogenic differentiation medium containing 0-, 2-, and 10-mm GlcN. Morphometric analysis and examination of gene and protein expression indicated that treatment of hydrogel cultures with 2-mm GlcN for 21 days significantly increased EB size, levels of aggrecan mRNA, and tissue-specific extracellular matrix accumulation. GlcN can induce multiple aspects of cell behavior and optimal GlcN concentrations can be beneficial for directing the differentiation and tissue formation of ES cells.

Animals↗

PubMed2006

Chondrogenic differentiation of human embryonic stem cell-derived cells in arginine-glycine-aspartate-modified hydrogels.

Human embryonic stem cells (hESCs) have the potential to self-renew and generate multiple cell types, producing critical building blocks for tissue engineering and regenerative medicine applications. Here, we describe the efficient derivation and chondrogenic differentiation of mesenchymal-like cells from hESCs. These cells exhibit mesenchymal stem cell (MSC) surface markers, including CD29, CD44, CD105, and platelet-derived growth factor receptor-alpha. Under appropriate growth conditions, the hESC-derived cells proliferated without phenotypic changes and maintained MSC surface markers. The chondrogenic capacity of the cells was studied in pellet culture and after encapsulation in poly(ethylene glycol)-diacrylate (PEGDA) hydrogels with exogenous extracellular proteins or arginineglycine- aspartate (RGD)-modified PEGDA hydrogels. The hESC-derived cells exhibited growth factor- dependent matrix production in pellet culture but did not produce tissue characteristic of cartilage morphology. In PEGDA hydrogels containing exogenous hyaluronic acid or type I collagen, no significant cell growth or matrix production was observed. In contrast, when these cells were encapsulated in RGDmodified poly(ethylene glycol)hydrogels, neocartilage with basophilic extracellular matrix deposition was observed within 3 weeks of culture, producing cartilage-specific gene up-regulation and extracellular matrix production. Our results indicate that precursor cells characteristic of a MSC population can be cultured from differentiating hESCs through embryoid bodies, thus holding great promise for a potentially unlimited source of cells for cartilage tissue engineering.

Amino Acids↗

PubMed2005

Effects of three-dimensional culture and growth factors on the chondrogenic differentiation of murine embryonic stem cells.

Embryonic stem (ES) cells have the ability to self-replicate and differentiate into cells from all three germ layers, holding great promise for tissue regeneration applications. However, controlling the differentiation of ES cells and obtaining homogenous cell populations still remains a challenge. We hypothesize that a supportive three-dimensional (3D) environment provides ES cell-derived cells an environment that more closely mimics chondrogenesis in vivo. In the present study, the chondrogenic differentiation capability of ES cell-derived embryoid bodies (EBs) encapsulated in poly(ethylene glycol)-based (PEG) hydrogels was examined and compared with the chondrogenic potential of EBs in conventional monolayer culture. PEG hydrogel-encapsulated EBs and EBs in monolayer were cultured in vitro for up to 17 days in chondrogenic differentiation medium in the presence of transforming growth factor (TGF)-beta1 or bone morphogenic protein-2. Gene expression and protein analyses indicated that EB-PEG hydrogel culture upregulated cartilage-relevant markers compared with a monolayer environment and induction of chondrocytic phenotype was stimulated with TGF-beta1. Histology of EBs in PEG hydrogel culture with TGF-beta1 demonstrated basophilic extracellular matrix deposition characteristic of neocartilage. These findings suggest that EB-PEG hydrogel culture, with an appropriate growth factor, may provide a suitable environment for chondrogenic differentiation of intact ES cell-derived EBs.

Animals↗

PubMed2005

Abnormalities in cartilage and bone development in the Apert syndrome FGFR2(+/S252W) mouse.

Apert syndrome is an autosomal dominant disorder characterized by malformations of the skull, limbs and viscera. Two-thirds of affected individuals have a S252W mutation in fibroblast growth factor receptor 2 (FGFR2). To study the pathogenesis of this condition, we generated a knock-in mouse model with this mutation. The Fgfr2(+/S252W) mutant mice have abnormalities of the skeleton, as well as of other organs including the brain, thymus, lungs, heart and intestines. In the mutant neurocranium, we found a midline sutural defect and craniosynostosis with abnormal osteoblastic proliferation and differentiation. We noted ectopic cartilage at the midline sagittal suture, and cartilage abnormalities in the basicranium, nasal turbinates and trachea. In addition, from the mutant long bones, in vitro cell cultures grown in osteogenic medium revealed chondrocytes, which were absent in the controls. Our results suggest that altered cartilage and bone development play a significant role in the pathogenesis of the Apert syndrome phenotype.

Acrocephalosyndactylia↗

PubMed2005

The effect of incorporating RGD adhesive peptide in polyethylene glycol diacrylate hydrogel on osteogenesis of bone marrow stromal cells.

Advances in tissue engineering require biofunctional scaffolds that can not only provide cells with structural support, but also interact with cells in a biological manner. To achieve this goal, a frequently used cell adhesion peptide Arg-Gly-Asp (RGD) was covalently incorporated into poly(ethylene glycol) diacrylate (PEODA) hydrogel and its dosage effect (0.025, 1.25 and 2.5 mm) on osteogenesis of marrow stromal cells in a three-dimensional environment was examined. Expression of bone-related markers, osteocalcin (OCN) and Alkaline phosphatase (ALP), increased significantly as the RGD concentration increased. Compared with no RGD, 2.5 mm RGD group showed a 1344% increase in ALP production and a 277% increase in OCN accumulation in the medium. RGD helped MSCs maintain cbfa-1 expression when shifted from a two-dimensional environment to a three-dimensional environment. Soluble RGD was found to completely block the mineralization of marrow stromal cells, as manifested by quantitative calcium assay, phosphorus elemental analysis and Von Kossa staining. In conclusion, we have demonstrated that RGD-conjugated PEODA hydrogel promotes the osteogenesis of MSCs in a dosage-dependent manner, with 2.5 mm being optimal concentration.

Alkaline Phosphatase↗

PubMed2005

Musculoskeletal differentiation of cells derived from human embryonic germ cells.

Stem cells have the potential to significantly improve cell and tissue regeneration therapies, but little is understood about how to control their behavior. We investigated the potential differentiation capability of cells derived from human embryonic germ (EG) cells into musculoskeletal lineages by providing a three-dimensional environment with increased cell-cell contact and growth factors. Cells were clustered into pellets to mimic the mesenchyme condensation process during limb development. LVEC cells, an embryoid body-derived (EBD) cell culture generated from EG cells, were cultured in micromass pellets for 21 days in the presence of bone morphogenetic protein 2 (BMP2) and/or transforming growth factor beta-3 (TGFbeta3). Gene expression for cartilage-, bone-, and muscle-specific matrix proteins--including collagen types I, II, III, IX, X; aggrecan; cartilage proteoglycan link protein; cartilage oligomeric protein; chondroitin sulfate-4-S; and myf5--was upregulated in the pellets treated with TGFbeta3, while mRNAs for neurofilament heavy (NFH), a neuron marker, and flk-1, a hematopoietic marker, decreased. Total collagen and proteoglycan production exhibited a time-dependent increase in the pellets treated with TGFbeta3, further confirming the expression of characteristic musculoskeletal markers. Furthermore, our results indicate the ability to select or differentiate stem cells toward a musculoskeletal lineage from a heterogenous EBD cell line.

Cartilage↗

PubMed2004

Injectable cartilage tissue engineering.

Cartilage is the tissue that lines the surface of bones in articulating joints, allowing painless joint movement. Cartilage loss is an increasingly significant problem, particularly with the ageing of active baby boomers, with few efficacious treatments available at present. Tissue engineering is a field that has evolved over recent years to combat tissue loss by providing a living tissue equivalent or substitute that can mimic the properties of the lost tissue. The general strategy of tissue engineering is to place cells on a biomaterial scaffold that is designed to promote cell function and form new tissue. This review describes the status of materials that are available as injectable scaffolds for tissue engineering and the numerous cell types that can be applied to cartilage repair, including cells derived from cartilage and stem cells. The current state of injectable cartilage tissue engineering and the hurdles that remain for widespread clinical application are discussed.

Animals↗

PubMed2003

In vitro chondrogenesis of bone marrow-derived mesenchymal stem cells in a photopolymerizing hydrogel.

Mesenchymal stem cells (MSCs) from skeletally mature goats were encapsulated in a photopolymerizing poly(ethylene glycol)-based hydrogel and cultured with or without transforming growth factor beta1 (TGF) to study the potential for chondrogenesis in a hydrogel scaffold system amenable to minimally invasive implantation. Chondrogenic differentiation was evaluated by histological, biochemical, and RNA analyses for the expression of cartilage extracellular matrix components. The two control groups studied were MSCs cultured in monolayer and MSCs encapsulated in the hydrogel and cultured for 6 weeks in chondrogenic medium without TGF-beta1 (6wk-TGF). The three experimental time points for encapsulated cells studied were 0 days (0d), 3 weeks, and 6 weeks in chondrogenic medium with TGF-beta1 at 10 ng/ml (3wk+TGF and 6wk+TGF). MSCs proliferated in the hydrogels with TGF-beta1. Glycosaminoglycan (GAG) and total collagen content of the hydrogels increased to 3.5% dry weight and 5.0% dry weight, respectively, in 6wk+TGF constructs. Immunohistochemistry revealed the presence of aggrecan, link protein, and type II collagen. Upregulation of aggrecan and type II collagen gene expression compared with monolayer MSCs was demonstrated. Type I collagen gene expression decreased from 3 to 6 weeks in the presence of TGF-beta1. 6wk-TGF hydrogels produced no GAG and only moderate amounts of collagen. However, immunohistochemistry and RT-PCR demonstrated a small amount of spontaneous differentiation in this control group. This study demonstrates the ability to encapsulate MSCs to form cartilage-like tissue in vitro in a photopolymerizing hydrogel. This system may be useful for minimally invasive implantation, MSC differentiation, and engineering of composite tissue structures with multiple cellular phenotypes.

Animals↗