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Tendon proper- and peritenon-derived progenitor cells have unique tenogenic properties.

Mienaltowski MJ, Adams SM, Birk DE - Stem Cell Res Ther (2014)

Bottom Line: Tendon construct ultrastructure was also compared after 45 days.It also was found that peritenon-derived progenitors secrete factor(s) stimulatory to tenocytes and tendon proper progenitors.Data demonstrate that, relative to peritenon-derived progenitors, tendon proper progenitors have greater potential for forming functional tendon-like tissue.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: Multipotent progenitor populations exist within the tendon proper and peritenon of the Achilles tendon. Progenitor populations derived from the tendon proper and peritenon are enriched with distinct cell types that are distinguished by expression of markers of tendon and vascular or pericyte origins, respectively. The objective of this study was to discern the unique tenogenic properties of tendon proper- and peritenon-derived progenitors within an in vitro model. We hypothesized that progenitors from each region contribute differently to tendon formation; thus, when incorporated into a regenerative model, progenitors from each region will respond uniquely. Moreover, we hypothesized that cell populations like progenitors were capable of stimulating tenogenic differentiation, so we generated conditioned media from these cell types to analyze their stimulatory potentials.

Methods: Isolated progenitors were seeded within fibrinogen/thrombin gel-based constructs with or without supplementation with recombinant growth/differentiation factor-5 (GDF5). Early and late in culture, gene expression of differentiation markers and matrix assembly genes was analyzed. Tendon construct ultrastructure was also compared after 45 days. Moreover, conditioned media from tendon proper-derived progenitors, peritenon-derived progenitors, or tenocytes was applied to each of the three cell types to determine paracrine stimulatory effects of the factors secreted from each of the respective cell types.

Results: The cell orientation, extracellular domain and fibril organization of constructs were comparable to embryonic tendon. The tendon proper-derived progenitors produced a more tendon-like construct than the peritenon-derived progenitors. Seeded tendon proper-derived progenitors expressed greater levels of tenogenic markers and matrix assembly genes, relative to peritenon-derived progenitors. However, GDF5 supplementation improved expression of matrix assembly genes in peritenon progenitors and structurally led to increased mean fibril diameters. It also was found that peritenon-derived progenitors secrete factor(s) stimulatory to tenocytes and tendon proper progenitors.

Conclusions: Data demonstrate that, relative to peritenon-derived progenitors, tendon proper progenitors have greater potential for forming functional tendon-like tissue. Furthermore, factors secreted by peritenon-derived progenitors suggest a trophic role for this cell type as well. Thus, these findings highlight the synergistic potential of including these progenitor populations in restorative tendon engineering strategies.

No MeSH data available.


Progenitor-derived matrix assembly is ultrastructurally similar to that of embryonic tendon. Ultrastructure was examined by cross-sectional images. In both the E15 to E17 Achilles tendon (A) and the progenitor constructs (B-E), collagen fibril synthesis and fiber assembly by cell processes are evident with fibers labeled with black dashed-line ovals (A-E). Panels: Embryonic Achilles tendon (A), tendon proper (TP)-derived progenitor-seeded construct (B), peritenon (PERI)-derived progenitor-seeded construct (C),TP-derived progenitor-seeded construct supplemented with GDF5 (D), peritenon (PERI)-derived progenitor-seeded construct supplemented with GDF5 (E). ETC: embryonic tendon cell; TP: tendon proper-derived progenitor; PP: peritenon-derived progenitor (Bar: 1 μm). E, embryonic day; GDF5, growth differentiation factor 5.
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Figure 2: Progenitor-derived matrix assembly is ultrastructurally similar to that of embryonic tendon. Ultrastructure was examined by cross-sectional images. In both the E15 to E17 Achilles tendon (A) and the progenitor constructs (B-E), collagen fibril synthesis and fiber assembly by cell processes are evident with fibers labeled with black dashed-line ovals (A-E). Panels: Embryonic Achilles tendon (A), tendon proper (TP)-derived progenitor-seeded construct (B), peritenon (PERI)-derived progenitor-seeded construct (C),TP-derived progenitor-seeded construct supplemented with GDF5 (D), peritenon (PERI)-derived progenitor-seeded construct supplemented with GDF5 (E). ETC: embryonic tendon cell; TP: tendon proper-derived progenitor; PP: peritenon-derived progenitor (Bar: 1 μm). E, embryonic day; GDF5, growth differentiation factor 5.

Mentions: This series of experiments tested the hypothesis that the tendon proper and peritenon progenitors have unique tenogenic properties when incorporated into the in vitro regenerative model. The structures of the engineered tissues and the developing tendons were analyzed using transmission electron microscopy. The progenitor-seeded constructs generated tendon-like tissues with a structure similar to that of embryonic tendon. That is, after 45 days in culture, the ultrastructure analysis of cross-sectional images from the mid-regions of the constructs shows that cells seeded within the constructs have processes projecting into the matrix compartmentalizing the extracellular matrix and organizing collections of fibrils into fibers, all of which is comparable to that observed in embryonic (E15 to E17) Achilles tendon (Figure 2A-E). Qualitatively, this is seen for constructs seeded with tendon proper- or peritenon-derived progenitors when cultured with or without supplementation of GDF5.


Tendon proper- and peritenon-derived progenitor cells have unique tenogenic properties.

Mienaltowski MJ, Adams SM, Birk DE - Stem Cell Res Ther (2014)

Progenitor-derived matrix assembly is ultrastructurally similar to that of embryonic tendon. Ultrastructure was examined by cross-sectional images. In both the E15 to E17 Achilles tendon (A) and the progenitor constructs (B-E), collagen fibril synthesis and fiber assembly by cell processes are evident with fibers labeled with black dashed-line ovals (A-E). Panels: Embryonic Achilles tendon (A), tendon proper (TP)-derived progenitor-seeded construct (B), peritenon (PERI)-derived progenitor-seeded construct (C),TP-derived progenitor-seeded construct supplemented with GDF5 (D), peritenon (PERI)-derived progenitor-seeded construct supplemented with GDF5 (E). ETC: embryonic tendon cell; TP: tendon proper-derived progenitor; PP: peritenon-derived progenitor (Bar: 1 μm). E, embryonic day; GDF5, growth differentiation factor 5.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4230637&req=5

Figure 2: Progenitor-derived matrix assembly is ultrastructurally similar to that of embryonic tendon. Ultrastructure was examined by cross-sectional images. In both the E15 to E17 Achilles tendon (A) and the progenitor constructs (B-E), collagen fibril synthesis and fiber assembly by cell processes are evident with fibers labeled with black dashed-line ovals (A-E). Panels: Embryonic Achilles tendon (A), tendon proper (TP)-derived progenitor-seeded construct (B), peritenon (PERI)-derived progenitor-seeded construct (C),TP-derived progenitor-seeded construct supplemented with GDF5 (D), peritenon (PERI)-derived progenitor-seeded construct supplemented with GDF5 (E). ETC: embryonic tendon cell; TP: tendon proper-derived progenitor; PP: peritenon-derived progenitor (Bar: 1 μm). E, embryonic day; GDF5, growth differentiation factor 5.
Mentions: This series of experiments tested the hypothesis that the tendon proper and peritenon progenitors have unique tenogenic properties when incorporated into the in vitro regenerative model. The structures of the engineered tissues and the developing tendons were analyzed using transmission electron microscopy. The progenitor-seeded constructs generated tendon-like tissues with a structure similar to that of embryonic tendon. That is, after 45 days in culture, the ultrastructure analysis of cross-sectional images from the mid-regions of the constructs shows that cells seeded within the constructs have processes projecting into the matrix compartmentalizing the extracellular matrix and organizing collections of fibrils into fibers, all of which is comparable to that observed in embryonic (E15 to E17) Achilles tendon (Figure 2A-E). Qualitatively, this is seen for constructs seeded with tendon proper- or peritenon-derived progenitors when cultured with or without supplementation of GDF5.

Bottom Line: Tendon construct ultrastructure was also compared after 45 days.It also was found that peritenon-derived progenitors secrete factor(s) stimulatory to tenocytes and tendon proper progenitors.Data demonstrate that, relative to peritenon-derived progenitors, tendon proper progenitors have greater potential for forming functional tendon-like tissue.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: Multipotent progenitor populations exist within the tendon proper and peritenon of the Achilles tendon. Progenitor populations derived from the tendon proper and peritenon are enriched with distinct cell types that are distinguished by expression of markers of tendon and vascular or pericyte origins, respectively. The objective of this study was to discern the unique tenogenic properties of tendon proper- and peritenon-derived progenitors within an in vitro model. We hypothesized that progenitors from each region contribute differently to tendon formation; thus, when incorporated into a regenerative model, progenitors from each region will respond uniquely. Moreover, we hypothesized that cell populations like progenitors were capable of stimulating tenogenic differentiation, so we generated conditioned media from these cell types to analyze their stimulatory potentials.

Methods: Isolated progenitors were seeded within fibrinogen/thrombin gel-based constructs with or without supplementation with recombinant growth/differentiation factor-5 (GDF5). Early and late in culture, gene expression of differentiation markers and matrix assembly genes was analyzed. Tendon construct ultrastructure was also compared after 45 days. Moreover, conditioned media from tendon proper-derived progenitors, peritenon-derived progenitors, or tenocytes was applied to each of the three cell types to determine paracrine stimulatory effects of the factors secreted from each of the respective cell types.

Results: The cell orientation, extracellular domain and fibril organization of constructs were comparable to embryonic tendon. The tendon proper-derived progenitors produced a more tendon-like construct than the peritenon-derived progenitors. Seeded tendon proper-derived progenitors expressed greater levels of tenogenic markers and matrix assembly genes, relative to peritenon-derived progenitors. However, GDF5 supplementation improved expression of matrix assembly genes in peritenon progenitors and structurally led to increased mean fibril diameters. It also was found that peritenon-derived progenitors secrete factor(s) stimulatory to tenocytes and tendon proper progenitors.

Conclusions: Data demonstrate that, relative to peritenon-derived progenitors, tendon proper progenitors have greater potential for forming functional tendon-like tissue. Furthermore, factors secreted by peritenon-derived progenitors suggest a trophic role for this cell type as well. Thus, these findings highlight the synergistic potential of including these progenitor populations in restorative tendon engineering strategies.

No MeSH data available.