Project description:Growth plate chondrocytes were isolated from the distal metacarpus of young dairy cattle (all under 10 mo of age), the chondrocytes were released from the extracellular matrix by digestion with Collagenase P for 4 hours, and the various zones of the growth plate were separated by density centrifugation. The least-dense Hypertrophic Zone (HZ) cells were compared to the most-dense Reserve Zone (RZ) cells. 6 pairs of HZ vs RZ were compared by microarray. Experiment Overall Design: Growth plate chondrocytes were isolated from the distal metacarpus of young dairy cattle (all under 10 mo of age), the chondrocytes were released from the extracellular matrix by digestion with Collagenase P for 4 hours, and the various zones of the growth plate were separated by density centrifugation. The least-dense Hypertrophic Zone (HZ) cells were compared to the most-dense Reserve Zone (RZ) cells. Six independent sample pairs of HZ vs RZ were compared by microarray.
Project description:Growth plate chondrocytes were isolated from the distal metacarpus of young dairy cattle (all under 10 mo of age), the chondrocytes were released from the extracellular matrix by digestion with Collagenase P for 4 hours, and the various zones of the growth plate were separated by density centrifugation. The least-dense Hypertrophic Zone (HZ) cells were compared to the most-dense Reserve Zone (RZ) cells. 6 pairs of HZ vs RZ were compared by microarray.
Project description:In the growth plate, the reserve and perichondral zones have been hypothesized to have similar functions, but their exact functions are poorly understood. Our hypothesis was that significant differential gene expression exists between perichondral and reserve chondrocytes that may differentiate the respective functions of these two zones. Normal Sprague-Dawley rat growth plate chondrocytes from the perichondral zone (PC), reserve zone (RZ), proliferative zone (PZ), and hypertrophic zone (HZ) were isolated by laser microdissection and then subjected to microarray analysis. In order to most comprehensively capture the unique features of the two zones, we analyzed both the most highly expressed genes and those that were most significantly different from the proliferative zone (PZ) as a single comparator. Keywords: cell specific expression profiles
Project description:In the growth plate, the reserve and perichondral zones have been hypothesized to have similar functions, but their exact functions are poorly understood. Our hypothesis was that significant differential gene expression exists between perichondral and reserve chondrocytes that may differentiate the respective functions of these two zones. Normal Sprague-Dawley rat growth plate chondrocytes from the perichondral zone (PC), reserve zone (RZ), proliferative zone (PZ), and hypertrophic zone (HZ) were isolated by laser microdissection and then subjected to microarray analysis. In order to most comprehensively capture the unique features of the two zones, we analyzed both the most highly expressed genes and those that were most significantly different from the proliferative zone (PZ) as a single comparator. Experiment Overall Design: 2 microarray replicates were obtained for each zone, using pooled quantities of RNA from 3 rats each at 42 and 46 days of age.
Project description:Chondrocytes advance through the long bone growth plate in synchrony, allowing their segregation into one of four zones each corresponding to a different phase of maturation. Beginning from the epiphysis the recognized zones are: reserve, proliferative, prehypertrophic, and hypertrophic. A fifth zone, the perichondrium is located in apposition to the growth plate at its circumferential surface. The progression of chondrocytes through these zones, and hence growth, is regulated by a complex interplay of signaling pathways, defects in which lead to osteochondrodysplasias. At present, there are over 370 recognized skeletal disorders, slightly more than half of which have been explained at the molecular level. Through a combination of laser microdissection, linear mRNA amplification, and GeneChip analysis, our laboratory has acquired the zone specific expression profile of chondrocytes from the distal femoral growth plates of two normal patients. On average, transcripts interrogated by 12,193 or 18,454 GeneChip probe sets (out of a possible 54,000 probe sets) were present in patients 1 and 2, respectively. The homologous inter-array correlations for the log(2) intensities were M-bM-^IM-% 0.91M-BM-10.01. Keywords: Chondrocyte differentiation program. Populations of cells corresponding to the hypertrophic, prehypertrophic, proliferative, reserve, and perichondrium, were separately isolated by laser microdissection from cryostat sections of human growth plates using a Leica AS-LMD microscope. RNA was prepared from the isolated cells, amplified using a T7 linear amplification protocol, and analyzed by hybridization to Affymetrix microarrays. The distal femoral growth plate (left or right) was exclusively used for this study. Patient 1 of this study is an 11-10/12 year old Caucasian female and patient 2 is a 13-3/12 year old Caucasian male.
Project description:Chondrocytes advance through the long bone growth plate in synchrony, allowing their segregation into one of four zones each corresponding to a different phase of maturation. Beginning from the epiphysis the recognized zones are: reserve, proliferative, prehypertrophic, and hypertrophic. A fifth zone, the perichondrium is located in apposition to the growth plate at its circumferential surface. The progression of chondrocytes through these zones, and hence growth, is regulated by a complex interplay of signaling pathways, defects in which lead to osteochondrodysplasias. At present, there are over 370 recognized skeletal disorders, slightly more than half of which have been explained at the molecular level. Through a combination of laser microdissection, linear mRNA amplification, and GeneChip analysis, our laboratory has acquired the zone specific expression profile of chondrocytes from the distal femoral growth plates of two normal patients. On average, transcripts interrogated by 12,193 or 18,454 GeneChip probe sets (out of a possible 54,000 probe sets) were present in patients 1 and 2, respectively. The homologous inter-array correlations for the log(2) intensities were ≥ 0.91±0.01. Keywords: Chondrocyte differentiation program.
Project description:Articular and growth plate cartilage have comparable structures consisting of three distinct layers of chondrocytes, suggesting similar differentiation programs and therefore similar gene expression profiles. To address this hypothesis and to explore transcriptional changes that occur during the onset of articular and growth plate cartilage divergence, we used microdissection of 10-day-old rat proximal tibial epiphyses, microarray analysis, and bioinformatics to compare gene expression profiles in individual layers of articular and growth plate cartilage. We found that many genes that were spatially upregulated in intermediate/deep zone of articular cartilage were also spatially upregulated in resting zone of growth plate cartilage (overlap greater than expected by chance, P < 0.001). Interestingly, superficial zone of articular cartilage showed an expression profile with similarities to both proliferative and hypertrophic zones of growth plate cartilage (P < 0.001 each). Additionally, significant numbers of known proliferative zone markers (3 out of 6) and hypertrophic zone markers (27 out of 126) were spatially upregulated in superficial zone compared to intermediate/deep zone (more than expected by chance, P < 0.001 each). In conclusion, we provide evidence that intermediate/deep zone of articular cartilage has a gene expression profile more similar to resting zone of growth plate cartilage, whereas superficial zone has a gene expression profile more similar to proliferative and hypertrophic zones.
Project description:Axial growth of long bones occurs through a coordinated process of growth plate chondrocyte proliferation and differentiation. This maturation of chondrocytes is reflected in a zonal change in gene expression and cell morphology from resting to proliferative, prehypertrophic, and hypertrophic chondrocytes of the growth plate followed by ossification. A major experimental limitation in understanding growth plate biology and pathophysiology is the lack of a robust technique to isolate cells from the different zones, particularly from small animals. Here, we report on a new strategy for separating distinct chondrocyte populations from mouse growth plates. By transcriptome profiling of microdissected zones of growth plates, we identified novel, zone-specific cell surface markers and used these for flow cytometry and immunomagnetic cell separation to quantify, enrich, and characterize chondrocytes populations with respect to their differentiation status. This approach provides a novel platform to study cartilage development and characterize mouse growth plate chondrocytes to reveal unique cellular phenotypes of the distinct subpopulations within the growth plate.
Project description:Longitudinal bone growth depends upon the execution of an intricate series of cellular activities by epiphyseal growth plate chondrocytes. In order to better understand these coordinated events, microarray analysis was used to compare gene expression in chondrocytes isolated from the proliferative and hypertrophic zones of the avian growth plate. In this experiment we compared pooled samples of proliferative and hypertrophic chondrocytes isolated from the chick growth plate. The expression of 745 genes was found to differ 3-fold or greater at the 0.05 level of probability. Experiment Overall Design: We examined 8 samples using arrays: 4 from proliferative and 4 from hypertrophic chondrocytes.
Project description:Articular and growth plate cartilage have comparable structures consisting of three distinct layers of chondrocytes, suggesting similar differentiation programs and therefore similar gene expression profiles. To address this hypothesis and to explore transcriptional changes that occur during the onset of articular and growth plate cartilage divergence, we used microdissection of 10-day-old rat proximal tibial epiphyses, microarray analysis, and bioinformatics to compare gene expression profiles in individual layers of articular and growth plate cartilage. We found that many genes that were spatially upregulated in intermediate/deep zone of articular cartilage were also spatially upregulated in resting zone of growth plate cartilage (overlap greater than expected by chance, P < 0.001). Interestingly, superficial zone of articular cartilage showed an expression profile with similarities to both proliferative and hypertrophic zones of growth plate cartilage (P < 0.001 each). Additionally, significant numbers of known proliferative zone markers (3 out of 6) and hypertrophic zone markers (27 out of 126) were spatially upregulated in superficial zone compared to intermediate/deep zone (more than expected by chance, P < 0.001 each). In conclusion, we provide evidence that intermediate/deep zone of articular cartilage has a gene expression profile more similar to resting zone of growth plate cartilage, whereas superficial zone has a gene expression profile more similar to proliferative and hypertrophic zones. 10-day-old rat proximal tibial epiphyses were manually microdissected into articular cartilage superficial (SZ) and intermediate/deep (IDZ) zones and growth plate cartilage resting zone (RZ) for total RNA extraction and hybridization on Affymetrix microarrays. We used 10-day-old animals because, at this age, the secondary ossification center has recently begun to form and divides the epiphysis into articular cartilage distally and growth plate cartilage more centrally. The 4 SZ samples were taken from animals 5-8, respectively, whereas the 4 IDZ and 4 RZ samples were each taken from animals 1-2, 3-4, 5-6, and 7-8, respectively.