A phenotypic comparison of intervertebral disc and articular cartilage cells in the rat.

The basic molecular characteristics of intervertebral disc cells are still poorly defined. This study compared the phenotypes of nucleus pulposus (NP), annulus fibrosus (AF) and articular cartilage (AC) cells using rat coccygeal discs and AC from both young and aged animals and a combination of microarray, real-time RT-PCR and immunohistochemistry. Microarray analysis identified 63 genes with at least a fivefold difference in fluorescence intensity between the NP and AF cells and 41 genes with a fivefold or greater difference comparing NP cells and articular chondrocytes.

An in vitro organ culturing system for intervertebral disc explants with vertebral endplates: a feasibility study with ovine caudal discs.

Study Design: Whole ovine caudal intervertebral discs with vertebral endplates were cultured under uniaxial diurnal loading for 7 days.

Objectives: To establish and characterize an organ culture system for intervertebral discs, in which disc cells may be "maintained" in their native three-dimensional environment under load.

Summary Of Background Data: In vitro culturing of entire discs with preserved biologic and structural integrity would be a useful model to study the effects of nutrition and mechanical loading.

Chondrocyte gene expression under applied surface motion.

A cartilage bioreactor has been designed that is intended to approximate the kinematics of natural joints and allows for functional cartilage tissue engineering studies. In particular, interface motion can be generated by oscillation of a ball over the surface of a construct. The present study investigated the specific effect of applied articular motion on the gene expression of chondrocytes cultured in 3D scaffolds, with a particular emphasis on different superficial zone protein (SZP)/lubricin transcripts.

In vitro organ culture of the bovine intervertebral disc: effects of vertebral endplate and potential for mechanobiology studies.

Study Design: Whole bovine coccygeal discs were cultured under static load, with or without vertebral endplates (VEPs), and assessed for cell viability, biochemical stability, biosynthetic activity, and biosynthetic responsiveness to changes in mechanical load.

Objectives: To assess the effects of VEPs on biochemical and cellular stability of disc cells during in vitro culture of large disc explants. To determine whether cultured discs could respond to mechanical perturbation.

Fibrin-polyurethane composites for articular cartilage tissue engineering: a preliminary analysis.

In this study we investigated the use of a fibrin hydrogel to improve the potential of a polyurethane (PU) scaffold-based system for articular cartilage tissue engineering. PU-only ("no-fibrin") and PU-fibrin ("fibrin") composites were cultured for up to 28 days and analyzed for DNA content, glycosaminoglycan (GAG) content, type II collagen content, GAG release, and gene expression of aggrecan, collagen I, and collagen II. The use of fibrin allowed for higher viable cell-seeding efficiency (10% higher DNA content on day 2 in fibrin versus no-fibrin composites) and more even cell distribution on seeding, a more than 3-fold increase in the percentage of newly synthesized GAG retained in the constructs, and 2- to 6-fold higher levels of type II collagen and aggrecan gene expression through day 14.

The effects of short-term load duration on anabolic and catabolic gene expression in the rat tail intervertebral disc.

The goal of this study was to determine the time-dependent response of the intervertebral disc cells to in vivo dynamic compression. Forty-seven skeletally mature Wistar rats (>12 months old) were instrumented with an Ilizarov-type device spanning caudal disc 8-9. Using a load magnitude (1 MPa) and frequency (1.

Surface motion upregulates superficial zone protein and hyaluronan production in chondrocyte-seeded three-dimensional scaffolds.

A cartilage engineering bioreactor has been developed that provides joint-specific kinematics. This study investigated the effect of articular motion on the gene expression of superficial zone protein (SZP) and hyaluronan synthases (HASs) and on the release of SZP and hyaluronan of chondrocytes seeded onto biodegradable scaffolds. Cylindrical (8 x 4 mm) porous polyurethane scaffolds were seeded with bovine articular chondrocytes and subjected to static or dynamic compression, with and without articulation against a ceramic hip ball.

Anabolic and catabolic mRNA levels of the intervertebral disc vary with the magnitude and frequency of in vivo dynamic compression.

The goal of this study was to characterize the anabolic and catabolic mRNA response of the disc to dynamic loading to determine if variations in the magnitude and/or frequency of loading could elicit different cellular responses. Sixty-eight Wistar rats were instrumented with an Ilizarov-type device spanning caudal disc 8-9. Seventy-two hours after surgery, animals were anesthetized and loaded at either 1 or 0.

Effects of immobilization and dynamic compression on intervertebral disc cell gene expression in vivo.

Study Design: An in vivo analysis of the intervertebral disc's cellular response to dynamic compression and immobilization was performed using a rat-tail model.

Objective: To assess the effects of immobilization and short-term dynamic compression on intervertebral disc cell expression of anabolic and catabolic genes.

Summary Of Background Data: Static compressive loads applied in vivo alter the composition of the disc matrix and cell viability in a dose-dependent manner.