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Regeneration of Articular Cartilage in Lizard Knee from Resident Stem/Progenitor Cells.

Alibardi L - Int J Mol Sci (2015)

Bottom Line: In healthy long bones of adult lizards, the addition of new chondrocytes from the stem cells population in the articular cartilage and the metaphyseal growth plate likely allows for slow, continuous longitudinal growth.When the knee is injured in the adult lizard, new populations of chondrocytes actively producing chondroitin sulfate proteoglycan are derived from these stem cells to allow for the formation of completely new cartilaginous epiphyses, possibly anticipating the re-formation of secondary centers in later stages.The study suggests that in this lizard species, the regenerative ability of the epiphyses is a pre-adaptation to the regeneration of the articular cartilage.

View Article: PubMed Central - PubMed

Affiliation: Comparative Histolab and Department of Bigea, University of Bologna, via Selmi 3, 40126 Bologna, Italy. lorenzo.alibardi@unibo.it.

ABSTRACT
The epiphysis of femur and tibia in the lizard Podarcis muralis can extensively regenerate after injury. The process involves the articular cartilage and metaphyseal (growth) plate after damage. The secondary ossification center present between the articular cartilage and the growth plate is replaced by cartilaginous epiphyses after about one month of regeneration at high temperature. The present study analyzes the origin of the chondrogenic cells from putative stem cells located in the growing centers of the epiphyses. The study is carried out using immunocytochemistry for the detection of 5BrdU-labeled long retaining cells and for the localization of telomerase, an enzyme that indicates stemness. The observations show that putative stem cells retaining 5BrdU and positive for telomerase are present in the superficial articular cartilage and metaphyseal growth plate located in the epiphyses. This observation suggests that these areas represent stem cell niches lasting for most of the lifetime of lizards. In healthy long bones of adult lizards, the addition of new chondrocytes from the stem cells population in the articular cartilage and the metaphyseal growth plate likely allows for slow, continuous longitudinal growth. When the knee is injured in the adult lizard, new populations of chondrocytes actively producing chondroitin sulfate proteoglycan are derived from these stem cells to allow for the formation of completely new cartilaginous epiphyses, possibly anticipating the re-formation of secondary centers in later stages. The study suggests that in this lizard species, the regenerative ability of the epiphyses is a pre-adaptation to the regeneration of the articular cartilage.

No MeSH data available.


Related in: MedlinePlus

TRITC immunofluorescence for Long Retaining Cells (LRC) in normal articular surfaces of knees. (A) sparsely labeled cells (arrows) are seen on the surface of the femur (outlined by dashes; di, diaphysis), metaphyseal growth plate (arrowheads, asterisks indicate non-specific labeling of the mineralized matrix), and meniscus (me, double arrowheads). 50 µm; (B) distribution of labeled cells (arrows) in the articular surface (outlined by dashes) and metaphyseal growth plate (arrowheads). di, diaphysis. Bar, 50 µm; (C) detail on labeled cells of the superficial region of the articular cartilage (arrow) and serial cartilage (arrowhead) of the metaphyseal growth plate. Asterisks indicate non-specific labeling of the mineralized matrix. Bar, 25 µm; (D) control section with indicated the position of the articular cartilage surface (arrow) and metaphyseal growth plate (arrowhead). Bar, 25 µm.
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ijms-16-20731-f004: TRITC immunofluorescence for Long Retaining Cells (LRC) in normal articular surfaces of knees. (A) sparsely labeled cells (arrows) are seen on the surface of the femur (outlined by dashes; di, diaphysis), metaphyseal growth plate (arrowheads, asterisks indicate non-specific labeling of the mineralized matrix), and meniscus (me, double arrowheads). 50 µm; (B) distribution of labeled cells (arrows) in the articular surface (outlined by dashes) and metaphyseal growth plate (arrowheads). di, diaphysis. Bar, 50 µm; (C) detail on labeled cells of the superficial region of the articular cartilage (arrow) and serial cartilage (arrowhead) of the metaphyseal growth plate. Asterisks indicate non-specific labeling of the mineralized matrix. Bar, 25 µm; (D) control section with indicated the position of the articular cartilage surface (arrow) and metaphyseal growth plate (arrowhead). Bar, 25 µm.

Mentions: After one week of pulse and three-and-a-half weeks of chase, some labeled nuclei of chondrocytes were still observed in normal knees, mainly sparsely along the surface of the articular cartilage of the femur and tibia. Labeled nuclei were also seen in the serial cartilage (resting and proliferating region) of the metaphyseal growth plate (arrows and arrowheads in Figure 4A,B). The labeling in the latter was a bit disturbed by the non-specific absorption of the fluorescent dye in the calcified cartilage (probably by the absorbing spongy surface formed during sectioning), but at higher magnification the nuclear labeling was evident (Figure 4C). Although less numerous, intensely labeled cells were also sparse in the lower layers of the articular cartilage and labeled cells were detected mainly along the perimeter of the meniscus and in the bone marrow. No labeling was present in control sections (Figure 4D).


Regeneration of Articular Cartilage in Lizard Knee from Resident Stem/Progenitor Cells.

Alibardi L - Int J Mol Sci (2015)

TRITC immunofluorescence for Long Retaining Cells (LRC) in normal articular surfaces of knees. (A) sparsely labeled cells (arrows) are seen on the surface of the femur (outlined by dashes; di, diaphysis), metaphyseal growth plate (arrowheads, asterisks indicate non-specific labeling of the mineralized matrix), and meniscus (me, double arrowheads). 50 µm; (B) distribution of labeled cells (arrows) in the articular surface (outlined by dashes) and metaphyseal growth plate (arrowheads). di, diaphysis. Bar, 50 µm; (C) detail on labeled cells of the superficial region of the articular cartilage (arrow) and serial cartilage (arrowhead) of the metaphyseal growth plate. Asterisks indicate non-specific labeling of the mineralized matrix. Bar, 25 µm; (D) control section with indicated the position of the articular cartilage surface (arrow) and metaphyseal growth plate (arrowhead). Bar, 25 µm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4613228&req=5

ijms-16-20731-f004: TRITC immunofluorescence for Long Retaining Cells (LRC) in normal articular surfaces of knees. (A) sparsely labeled cells (arrows) are seen on the surface of the femur (outlined by dashes; di, diaphysis), metaphyseal growth plate (arrowheads, asterisks indicate non-specific labeling of the mineralized matrix), and meniscus (me, double arrowheads). 50 µm; (B) distribution of labeled cells (arrows) in the articular surface (outlined by dashes) and metaphyseal growth plate (arrowheads). di, diaphysis. Bar, 50 µm; (C) detail on labeled cells of the superficial region of the articular cartilage (arrow) and serial cartilage (arrowhead) of the metaphyseal growth plate. Asterisks indicate non-specific labeling of the mineralized matrix. Bar, 25 µm; (D) control section with indicated the position of the articular cartilage surface (arrow) and metaphyseal growth plate (arrowhead). Bar, 25 µm.
Mentions: After one week of pulse and three-and-a-half weeks of chase, some labeled nuclei of chondrocytes were still observed in normal knees, mainly sparsely along the surface of the articular cartilage of the femur and tibia. Labeled nuclei were also seen in the serial cartilage (resting and proliferating region) of the metaphyseal growth plate (arrows and arrowheads in Figure 4A,B). The labeling in the latter was a bit disturbed by the non-specific absorption of the fluorescent dye in the calcified cartilage (probably by the absorbing spongy surface formed during sectioning), but at higher magnification the nuclear labeling was evident (Figure 4C). Although less numerous, intensely labeled cells were also sparse in the lower layers of the articular cartilage and labeled cells were detected mainly along the perimeter of the meniscus and in the bone marrow. No labeling was present in control sections (Figure 4D).

Bottom Line: In healthy long bones of adult lizards, the addition of new chondrocytes from the stem cells population in the articular cartilage and the metaphyseal growth plate likely allows for slow, continuous longitudinal growth.When the knee is injured in the adult lizard, new populations of chondrocytes actively producing chondroitin sulfate proteoglycan are derived from these stem cells to allow for the formation of completely new cartilaginous epiphyses, possibly anticipating the re-formation of secondary centers in later stages.The study suggests that in this lizard species, the regenerative ability of the epiphyses is a pre-adaptation to the regeneration of the articular cartilage.

View Article: PubMed Central - PubMed

Affiliation: Comparative Histolab and Department of Bigea, University of Bologna, via Selmi 3, 40126 Bologna, Italy. lorenzo.alibardi@unibo.it.

ABSTRACT
The epiphysis of femur and tibia in the lizard Podarcis muralis can extensively regenerate after injury. The process involves the articular cartilage and metaphyseal (growth) plate after damage. The secondary ossification center present between the articular cartilage and the growth plate is replaced by cartilaginous epiphyses after about one month of regeneration at high temperature. The present study analyzes the origin of the chondrogenic cells from putative stem cells located in the growing centers of the epiphyses. The study is carried out using immunocytochemistry for the detection of 5BrdU-labeled long retaining cells and for the localization of telomerase, an enzyme that indicates stemness. The observations show that putative stem cells retaining 5BrdU and positive for telomerase are present in the superficial articular cartilage and metaphyseal growth plate located in the epiphyses. This observation suggests that these areas represent stem cell niches lasting for most of the lifetime of lizards. In healthy long bones of adult lizards, the addition of new chondrocytes from the stem cells population in the articular cartilage and the metaphyseal growth plate likely allows for slow, continuous longitudinal growth. When the knee is injured in the adult lizard, new populations of chondrocytes actively producing chondroitin sulfate proteoglycan are derived from these stem cells to allow for the formation of completely new cartilaginous epiphyses, possibly anticipating the re-formation of secondary centers in later stages. The study suggests that in this lizard species, the regenerative ability of the epiphyses is a pre-adaptation to the regeneration of the articular cartilage.

No MeSH data available.


Related in: MedlinePlus