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Results for “NASA Discipline Cell Biotechnology”

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At least 19 recordsLinked to original sources

PubMed2005

Comparison of genotoxic damage in monolayer cell cultures and three-dimensional tissue-like cell assemblies.

Assessing the biological risks associated with exposure to the high-energy charged particles encountered in space is essential for the success of long-term space exploration. Although prokaryotic and eukaryotic cell models developed in our laboratory and others have advanced our understanding of many aspects of genotoxicity, in vitro models are needed to assess the risk to humans from space radiation insults. Such models must be representative of the cellular interactions present in tissues and capable of quantifying genotoxic damage. Toward this overall goal, the objectives of this study were to examine the effect of the localized microenvironment of cells, cultured as either 2-dimensional (2D) monolayers or 3-dimensional (3D) aggregates, on the rate and type of genotoxic damage resulting from exposure to Fe-charged particles, a significant portion of space radiation. We used rodent transgenic cell lines containing 50-70 copies of a LacI transgene to provide the enhanced sensitivity required to quantify mutational frequency and type in the 1100-bp LacI target as well as assessment of DNA damage to the entire 45-kbp construct. Cultured cells were exposed to high energy Fe charged particles at Brookhaven National Laboratory's Alternating Gradient Synchrotron facility for a total dose ranging from 0.1 to 2 Gy and allowed to recover for 0-7 days, after which mutational type and frequency were evaluated. The mutational frequency was found to be higher in 3D samples than in 2D samples at all radiation doses. Mutational frequency also was higher at 7 days after irradiation than immediately after exposure. DNA sequencing of the mutant targets revealed that deletional mutations contributed an increasingly high percentage (up to 27%) of all mutations in cells as the dose was increased from 0.5 to 2 Gy. Several mutants also showed large and complex deletions in multiple locations within the LacI target. However, no differences in mutational type were found between the 2D and the 3D samples. These 3D tissue-like model systems can reduce the uncertainty involved in extrapolating risk between in vitro cellular and in vivo models.

Animals↗

PubMed2004

Inhibition of cross-bridge formation has no effect on contraction-associated phosphorylation of p38 MAPK in mouse skeletal muscle.

Mitogen-activated protein kinases (MAPKs), in particular p38 MAPK, are phosphorylated in response to contractile activity, yet the mechanism for this is not understood. We tested the hypothesis that the force of contraction is responsible for p38 MAPK phosphorylation in skeletal muscle. Extensor digitorum longus (EDL) muscles isolated from adult male Swiss Webster mice were stimulated at fixed length at 10 Hz for 15 min and then subjected to Western blot analysis for the phosphorylation of p38 MAPK and ERK1/2. Contralateral muscles were fixed at resting length and were not stimulated. Stimulated muscles showed a 2.5-fold increase in phosphorylated p38 MAPK relative to nonstimulated contralateral controls, and there was no change in the phosphorylation of ERK1/2. When contractile activity was inhibited with N-benzyl-p-toluene sulfonamide (BTS), a specific inhibitor of actomyosin ATPase, force production decreased in both a time- and concentration-dependent manner. Preincubation with 25, 75, and 150 microM BTS caused 78+/-4%, 97+/-0.2%, and 99+/-0.2% inhibition in contractile force, respectively, and was stable after 30 min of treatment. Fluorescence measurements demonstrated that Ca2+ cycling was minimally affected by BTS treatment. Surprisingly, BTS did not suppress the level of p38 MAPK phosphorylation in stimulated muscles. These data do not support the view that force generation per se activates p38 MAPK and suggest that other events associated with contraction must be responsible.

Animals↗

PubMed2004

A modular suite of hardware enabling spaceflight cell culture research.

BioServe Space Technologies, a NASA Research Partnership Center (RPC), has developed and operated various middeck payloads launched on 23 shuttle missions since 1991 in support of commercial space biotechnology projects. Modular cell culture systems are contained within the Commercial Generic Bioprocessing Apparatus (CGBA) suite of flight-qualified hardware, compatible with Space Shuttle, SPACEHAB, Spacelab and International Space Station (ISS) EXPRESS Rack interfaces. As part of the CGBA family, the Isothermal Containment Module (ICM) incubator provides thermal control, data acquisition and experiment manipulation capabilities, including accelerometer launch detection for automated activation and thermal profiling for culture incubation and sample preservation. The ICM can accommodate up to 8 individually controlled temperature zones. Command and telemetry capabilities allow real-time downlink of data and video permitting remote payload operation and ground control synchronization. Individual cell culture experiments can be accommodated in a variety of devices ranging from 'microgravity test tubes' or standard 100 mm Petri dishes, to complex, fed-batch bioreactors with automated culture feeding, waste removal and multiple sample draws. Up to 3 levels of containment can be achieved for chemical fixative addition, and passive gas exchange can be provided through hydrophobic membranes. Many additional options exist for designing customized hardware depending on specific science requirements.

Bioreactors↗

PubMed2004

Synthesis of proteoglycan 4 by chondrocyte subpopulations in cartilage explants, monolayer cultures, and resurfaced cartilage cultures.

OBJECTIVE: To quantify the levels of proteoglycan 4 (PRG4) expression by subpopulations of chondrocytes from superficial, middle, and deep layers of normal bovine calf cartilage in various culture systems. METHODS: Bovine calf articular cartilage discs or isolated cells were used in 1 of 3 systems of chondrocyte culture: explant, monolayer, or transplant, for 1-9 days. PRG4 expression was quantified by enzyme-linked immunosorbent assay of spent medium and localized by immunohistochemistry at the articular surface and within chondrocytes in explants and cultured cells. RESULTS: Superficial chondrocytes secreted much more PRG4 than did middle and deep chondrocytes in all cultures. The pattern of PRG4 secretion into superficial culture medium varied with the duration of culture, decreasing with time in explant culture (from approximately 25 microg/cm(2)/day on days 0-1 to approximately 3 microg/cm(2)/day on days 5-9), while increasing in monolayer culture (from approximately 1 pg/cell/day on days 0-1 to approximately 7 pg/cell/day on days 7-9) and tending to increase in transplant culture (reaching approximately 2 microg/cm(2)/day by days 7-9). In all of the culture systems, inclusion of ascorbic acid stimulated PRG4 secretion, and the source of PRG4 was immunolocalized to superficial cells. CONCLUSION: The results described here indicate that the phenotype of PRG4 secretion by chondrocytes in culture is generally maintained, in that PRG4 is expressed to a much greater degree by chondrocytes from the superficial zone than by those from the middle and deep zones. The marked up-regulation of PRG4 synthesis by ascorbic acid may have implications for cartilage homeostasis and prevention of osteoarthritic disease. Transplanting specialized cells that secrete PRG4 to a surface may impart functional lubrication and be generally applicable to many tissues in the body.

Animals↗

PubMed2005

Inhibition of integrative cartilage repair by proteoglycan 4 in synovial fluid.

OBJECTIVE: To determine the effects of the articular cartilage surface, as well as synovial fluid (SF) and its components, specifically proteoglycan 4 (PRG4) and hyaluronic acid (HA), on integrative cartilage repair in vitro. METHODS: Blocks of calf articular cartilage were harvested, some with the articular surface intact and others without. Some of the latter types of blocks were pretreated with trypsin, and then with bovine serum albumin, SF, PRG4, or HA. Immunolocalization of PRG4 on cartilage surfaces was performed after treatment. Pairs of similarly treated cartilage blocks were incubated in partial apposition for 2 weeks in medium supplemented with serum and (3)H-proline. Following culture, mechanical integration between apposed cartilage blocks was assessed by measuring adhesive strength, and protein biosynthesis and deposition were determined by incorporated (3)H-proline. RESULTS: Samples with articular surfaces in apposition exhibited little integrative repair compared with samples with cut surfaces in apposition. PRG4 was immunolocalized at the articular cartilage surface, but not in deeper, cut surfaces (without treatment). Cartilage samples treated with trypsin and then with SF or PRG4 exhibited an inhibition of integrative repair and positive immunostaining for PRG4 at treated surfaces compared with normal cut cartilage samples, while samples treated with HA exhibited neither inhibited integrative repair nor PRG4 at the tissue surfaces. Deposition of newly synthesized protein was relatively similar under conditions in which integration differed significantly. CONCLUSION: These results support the concept that PRG4 in SF, which normally contributes to cartilage lubrication, can inhibit integrative cartilage repair. This has the desirable effect of preventing fusion of apposing surfaces of articulating cartilage, but has the undesirable effect of inhibiting integrative repair.

Animals↗

PubMed2004

Modeled microgravity disrupts collagen I/integrin signaling during osteoblastic differentiation of human mesenchymal stem cells.

Spaceflight leads to reduced bone mineral density in weight bearing bones that is primarily attributed to a reduction in bone formation. We have previously demonstrated severely reduced osteoblastogenesis of human mesenchymal stem cells (hMSC) following 7 days culture in modeled microgravity (MMG). One potential mechanism for reduced osteoblastic differentiation is disruption of type I collagen (Col I)-integrin interactions and reduced integrin signaling. Integrins are heterodimeric transmembrane receptors that bind extracellular matrix (ECM) proteins and produce signals essential for proper cellular function, survival, and differentiation. Therefore, we investigated the effects of MMG on integrin expression and function in hMSC. We demonstrate that 7 days of culture in MMG leads to reduced expression of the ECM protein, Col I. Conversely, MMG consistently increases Col I-specific alpha2 and beta1 integrin protein expression. Despite this increase in integrin subunit expression, autophosphorylation of adhesion-dependent kinases, focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (PYK2), is significantly reduced. Activation of Akt protein kinase (Akt) is unaffected by the reduction in FAK activation. However, reduced downstream signaling via the Ras-mitogen activated protein kinase (MAPK) pathway is evidenced by a reduction in Ras and extracellular signal-related protein kinase (ERK) activation. Taken together, our findings indicate that MMG decreases integrin/MAPK signaling, which likely contributes to the observed reduction in osteoblastogenesis.

Cell Differentiation↗

PubMed2004

Hypoxia suppresses runx2 independent of modeled microgravity.

Bone loss is a consequence of skeletal unloading as seen in bed rest and space flight. Unloading decreases oxygenation and osteoblast differentiation/function in bone. Previously we demonstrated that simulation of unloading in vitro, by culturing differentiating mouse osteoblasts in a horizontal rotating wall vessel (RWV), results in suppressed expression of runx2, a master transcriptional regulator of osteoblast differentiation. However, the RWV is able to reproduce in a controlled fashion at least two aspects of disuse that are directly linked, model microgravity and hypoxia. Hypoxia in the RWV is indicated by reduced medium oxygen tension and increased expression of GAPDH and VEGF. To uncouple the role of model microgravity from hypoxia in suppressed runx2 expression, we cultured osteoblasts under modeled microgravity (oxygenated, horizontal RWV rotation), hypoxia (vertical RWV rotation), or both conditions (horizontal RWV rotation). The expression, DNA binding activity and promoter activity of runx2, was suppressed under hypoxic but not normoxic modeled microgravity RWV conditions. Consistent with a role for hypoxia in suppression of runx2, direct exposure to hypoxia alone is sufficient to suppress runx2 expression in osteoblasts grown in standard tissue culture plates. Taken together, our findings indicate that hypoxia associated with skeletal unloading could be major suppressor of runx2 expression leading to suppressed osteoblast differentiation and bone formation.

3T3 Cells↗

PubMed2004

Homozygous diploid deletion strains of Saccharomyces cerevisiae that determine lag phase and dehydration tolerance.

This study identifies genes that determine length of lag phase, using the model eukaryotic organism, Saccharomyces cerevisiae. We report growth of a yeast deletion series following variations in the lag phase induced by variable storage times after drying-down yeast on filters. Using a homozygous diploid deletion pool, lag times ranging from 0 h to 90 h were associated with increased drop-out of mitochondrial genes and increased survival of nuclear genes. Simple linear regression (R2 analysis) shows that there are over 500 genes for which > 70% of the variation can be explained by lag alone. In the genes with a positive correlation, such that the gene abundance increases with lag and hence the deletion strain is suitable for survival during prolonged storage, there is a strong predominance of nucleonic genes. In the genes with a negative correlation, such that the gene abundance decreases with lag and hence the strain may be critical for getting yeast out of the lag phase, there is a strong predominance of glycoproteins and transmembrane proteins. This study identifies yeast deletion strains with survival advantage on prolonged storage and amplifies our understanding of the genes critical for getting out of the lag phase.

Dehydration↗

PubMed2005

A cartilage growth mixture model for infinitesimal strains: solutions of boundary-value problems related to in vitro growth experiments.

A cartilage growth mixture (CGM) model is linearized for infinitesimal elastic and growth strains. Parametric studies for equilibrium and nonequilibrium boundary-value problems representing the in vitro growth of cylindrical cartilage constructs are solved. The results show that the CGM model is capable of describing the main biomechanical features of cartilage growth. The solutions to the equilibrium problems reveal that tissue composition, constituent pre-stresses, and geometry depend on collagen remodeling activity, growth symmetry, and differential growth. Also, nonhomogeneous growth leads to nonhomogeneous tissue composition and constituent pre-stresses. The solution to the nonequilibrium problem reveals that the tissue is nearly in equilibrium at all time points. The results suggest that the CGM model may be used in the design of tissue engineered cartilage constructs for the repair of cartilage defects; for example, to predict how dynamic mechanical loading affects the development of nonuniform properties during in vitro growth. Furthermore, the results lay the foundation for future analyses with nonlinear models that are needed to develop realistic models of cartilage growth.

Biomechanical Phenomena↗

PubMed2005

The rapid onset of elasticity during the assembly of the bacterial cell-division protein FtsZ.

FtsZ, a prokaryotic homolog of eukaryotic tubulin, is a major constituent of the bacterial Z-ring, which contracts the cell wall during cell division. Because the mechanical properties of FtsZ are unknown, its function in the maintenance and constriction of the Z-ring is not well understood. Here, quantitative rheometry shows that, at physiological concentrations, FtsZ filaments form, extremely rapidly, highly elastic networks within physiological time scales ( approximately minutes), much faster than other major dynamic cytoskeletal filaments, including microtubule, actin, and vimentin in eukaryotes. FtsZ networks display a relatively low viscosity and a high resilience against shear stresses, as well as an elasticity that depends weakly on concentration, G approximately C(0.57), a power-law dependence consistent with crosslinked flexible filaments. Calcium, whose intracellular concentration increases during bacterial division, further enhances the elasticity of FtsZ networks through filament bundling, an effect that occurs in the presence of GTP, not GDP. These studies suggest that FtsZ filaments have the toughness to provide strong mechanical support for the maintenance and circumferential constriction of the bacterial Z-ring.

Actins↗

PubMed2005

How actin crosslinking and bundling proteins cooperate to generate an enhanced cell mechanical response.

Actin-crosslinking proteins organize actin filaments into dynamic and complex subcellular scaffolds that orchestrate important mechanical functions, including cell motility and adhesion. Recent mutation studies have shown that individual crosslinking proteins often play seemingly non-essential roles, leading to the hypothesis that they have considerable redundancy in function. We report live-cell, in vitro, and theoretical studies testing the mechanical role of the two ubiquitous actin-crosslinking proteins, alpha-actinin and fascin, which co-localize to stress fibers and the basis of filopodia. Using live-cell particle tracking microrheology, we show that the addition of alpha-actinin and fascin elicits a cell mechanical response that is significantly greater than that originated by alpha-actinin or fascin alone. These live-cell measurements are supported by quantitative rheological measurements with reconstituted actin filament networks containing pure proteins that show that alpha-actinin and fascin can work in concert to generate enhanced cell stiffness. Computational simulations using finite element modeling qualitatively reproduce and explain the functional synergy of alpha-actinin and fascin. These findings highlight the cooperative activity of fascin and alpha-actinin and provide a strong rationale that an evolutionary advantage might be conferred by the cooperative action of multiple actin-crosslinking proteins with overlapping but non-identical biochemical properties. Thus the combination of structural proteins with similar function can provide the cell with unique properties that are required for biologically optimal responses.

Actins↗

PubMed2005

Evaluation of polydimethylsiloxane scaffolds with physiologically-relevant elastic moduli: interplay of substrate mechanics and surface chemistry effects on vascular smooth muscle cell response.

Polydimethylsiloxane (PDMS) is used extensively to study cell-substrate interactions because its mechanical properties are easily tuned in physiologically relevant ranges. However, changes in mechanical properties also modulate surface chemistry and cell response. Here, we correlate the mechanical and surface properties of PDMS to vascular smooth muscle cell (VSMC) behavior. We find that a 5-fold increase in base:crosslinker ratio leads to approximately 40-fold decrease in elastic modulus but no significant differences in surface wettability. However, when polyelectrolyte multilayers are adsorbed to promote cell adhesion, wettability varies inversely with substrate stiffness. Despite these differences in hydrophobicity, the amount of adsorbed protein remains the same. In the absence of serum, there is a 39% decrease in cell attachment and a 42% decrease in spreading as the elastic modulus decreases from 1.79 to 0.05 MPa. In the presence of serum or adsorbed fibronectin, the differences in attachment and spreading are diminished. This is not the case for the rate of serum-stimulated cell proliferation, which remains inversely dependent on crosslinker concentration. We conclude that for the range of crosslinker concentrations investigated, the surface properties dominate the initial cell attachment and spreading, whereas the mechanical properties influence the long-term cell growth.

Adsorption↗

PubMed2005

Concentrated hydroxyapatite inks for direct-write assembly of 3-D periodic scaffolds.

Hydroxyapatite (HA) scaffolds with a 3-D periodic architecture and multiscale porosity have been fabricated by direct-write assembly. Concentrated HA inks with tailored viscoelastic properties were developed to enable the construction of complex 3-D architectures comprised of self-supporting cylindrical rods in a layer-by-layer patterning sequence. By controlling their lattice constant and sintering conditions, 3-D periodic HA scaffolds were produced with a bimodal pore size distribution. Mercury intrusion porosimetry (MIP) was used to determine the characteristic pore size and volume associated with the interconnected pore channels between HA rods and the finer pores within the partially sintered HA rods.

Biocompatible Materials↗

PubMed2004

Rapid differentiation of NT2 cells in Sertoli-NT2 cell tissue constructs grown in the rotating wall bioreactor.

Cell replacement therapy is of great interest as a long-term treatment of neurodegenerative diseases such as Parkinson's disease (PD). We have previously shown that Sertoli cells (SC) provide neurotrophic support to transplants of dopaminergic fetal neurons and NT2N neurons, derived from the human clonal precursors cell line NTera2/D1 (NT2), which differentiate into dopaminergic NT2N neurons when exposed to retinoic acid. We have created SC-NT2 cell tissue constructs cultured in the high aspect ratio vessel (HARV) rotating wall bioreactor. Sertoli cells, NT2, and SC plus NT2 cells combined in starting ratios of 1:1, 1:2, 1:4 and 1:8 were cultured in the HARV in DMEM with 10% fetal bovine serum and 1% growth factor reduced Matrigel for 3 days, without retinoic acid. Conventional, non-HARV, cultures grown in the same culture medium were used as controls. The presence of tyrosine hydroxylase (TH) was assessed in all culture conditions. Sertoli-neuron-aggregated-cell (SNAC) tissue constructs grown at starting ratios of 1:1 to 1:4 contained a significant amount of TH after 3 days of culture in the HARV. No TH was detected in SC HARV cultures, or SC, NT2 or SC-NT2 conventional co-cultures. Quantitative stereology of immunolabled 1:4 SNAC revealed that approximately 9% of NT2 cells differentiate into TH-positive (TH+) NT2N neurons after 3 days of culture in the HARV, without retinoic acid. SNAC tissue constructs also released dopamine (DA) when stimulated with KCl, suggesting that TH-positive NT2N neurons in the SNAC adopted a functional dopaminergic phenotype. SNAC tissue constructs may be an important source of dopaminergic neurons for neuronal transplantation.

Animals↗

PubMed2004

Neural stem cell differentiation in a cell-collagen-bioreactor culture system.

Neural stem cells and neural progenitors (NSCs/NPs) are capable of self-renewal and can give rise to both neurons and glia. Such cells have been isolated from the embryonic brain and immobilized in three dimensional collagen gels. The collagen-entrapped NSCs/NPs recapitulate CNS stem cell development and form functional synapses and neuronal circuits. However, the cell-collagen constructs from static conditions contain hypoxic, necrotic cores and the cells are short-lived. In the present study, NSCs/NPs isolated from embryonic day 13 rat cortical neuroepithelium are immobilized in type I collagen gels and cultured in NASA-designed rotating wall vessel (RWV) bioreactors for up to 9 weeks. Initially, during the first 2 weeks of culture, a lag phase of cellular growth and differentiation is observed in the RWV bioreactors. Accelerated growth and differentiation, with the cells beginning to form large aggregates (approximately 1 mm in diameter) without death cores, begins during the third week. The collagen-entrapped NSCs/NPs cultured in RWV show active neuronal generation followed by astrocyte production. After 6 weeks in rotary culture, the cell-collagen constructs contain over 10 fold greater nestin+ and GFAP+ cells and two-fold more TuJ1 gene expression than those found in static cultures. In addition, TuJ1+ neurons in RWV culture give rise to extensive neurite outgrowth and considerably more synapsin I+ pre-synaptic puncta surrounding MAP2+ cell bodies and dendrites. These results strongly suggest that the cell-collagen-bioreactor culture system supports long-term NSC/NP growth and differentiation, and RWV bioreactors can be useful in generating neural tissue like constructs, which may have the potential for cell replacement therapy.

Animals↗

PubMed2004

Impact of modeled microgravity on migration, differentiation, and cell cycle control of primitive human hematopoietic progenitor cells.

OBJECTIVE: Migration, proliferation, and differentiation of bone marrow (BM) hematopoietic stem cells (HSC) are important factors in maintaining hematopoietic homeostasis. Homeostatic control of erythrocytes and lymphocytes is perturbed in humans exposed to microgravity (micro-g), resulting in space flight-induced anemia and immunosuppression. We sought to determine whether any of these anomalies can be explained by micro-g-induced changes in migration, proliferation, and differentiation of human BM CD34+ cells, and whether such changes can begin to explain any of the shifts in hematopoietic homeostasis observed in astronauts. MATERIALS AND METHODS: BM CD34+ cells were cultured in modeled micro-g (mmicro-g) using NASA's rotating wall vessels (RWV), or in control cultures at earth gravity for 2 to 18 days. Cells were harvested at different times and CD34+ cells assessed for migration potential, cell-cycle kinetics and regulatory proteins, and maturation status. RESULTS: Culture of BM CD34+ cells in RWV for 2 to 3 days resulted in a significant reduction of stromal cell-derived factor 1 (SDF-1alpha)-directed migration, which correlated with decreased expression of F-actin. Modeled micro-g induced alterations in cell-cycle kinetics that were characterized by prolonged S phase and reduced cyclin A expression. Differentiation of primitive CD34+ cells cultured for 14 to 18 days in RWV favored myeloid cell development at the expense of erythroid development, which was significantly reduced compared to controls. CONCLUSIONS: These results illustrate that mmicro-g significantly inhibits the migration potential, cell-cycle progression, and differentiation patterns of primitive BM CD34+ cells, which may contribute to some of the hematologic abnormalities observed in humans during space flight.

Antigens, CD34↗

PubMed2005

A human stromal-based serum-free culture system supports the ex vivo expansion/maintenance of bone marrow and cord blood hematopoietic stem/progenitor cells.

OBJECTIVE: We investigated the role of human stromal layers (hu-ST) on the ex vivo expansion/maintenance of human hematopoietic stem/progenitor cells (HSC) from adult bone marrow (BM) and umbilical cord blood (CB). MATERIALS AND METHODS: BM and CB CD34(+)-enriched cells were cultured in serum-free medium supplemented with SCF, bFGF, LIF, and Flt-3, in the presence or absence of stroma, and analyzed for proliferation, phenotype, and clonogenic potential. RESULTS: Significant expansion of BM and CB CD34(+) and CD34(+)CD38(-) cells were achieved in the presence of hu-ST. The differentiative potential of both BM and CB CD34(+)-enriched cells cocultured with hu-ST was primarily shifted toward the myeloid lineage, while maintaining/expanding a CD7(+) population. Clonogenic analysis of the expanded cells showed increases in progenitors of the myeloid lineage, including colony-forming unit-granulocyte, macrophage (CFU-GM) and colony-forming unit-granulocyte, erythroid, macrophage, megakaryocyte (CFU-Mix) for both BM (stroma and stroma-free conditions) and CB cells in the presence of stroma. CONCLUSIONS: These results indicate that adult hu-ST in the presence of appropriate cytokines can be used to efficiently expand/maintain myeloid and lymphoid cell populations from human BM and CB HSC.

Antigens, CD↗

PubMed2005

Characterization of human nasal septal chondrocytes cultured in alginate.

BACKGROUND: After serial passages in monolayer, chondrocytes dedifferentiate into a fibroblast-like phenotype. Our objective was to determine if culture in alginate affects the phenotype of dedifferentiated human nasal septal chondrocytes. STUDY DESIGN: Human nasal septal chondrocytes were seeded at low density and passaged in monolayer culture. At passages (P) 1, 2, and 3 a portion of cells were cultured in alginate. Collagen, glycosaminoglycan (GAG), and DNA production were assessed. RESULTS: Chondrocytes in alginate proliferated less yet produced higher levels of GAG and collagen than those in monolayer culture. Alginate encapsulated P1 chondrocytes stained strongly for GAG and collagen type II, and minimally for collagen type I. Monolayer cells at P0 and P1 stained positively for collagen type II. All monolayer passages stained positive for collagen type I with minimal GAG staining. CONCLUSIONS: Compared with monolayer culture, alginate stimulates deposition of GAG and collagen type II, and supports the chondrocyte phenotype through P1, but does not promote redifferentiation.

Alginates↗