Limits...
Enhanced collagen type I synthesis by human tenocytes subjected to periodic in vitro mechanical stimulation.

Huisman E, Lu A, McCormack RG, Scott A - BMC Musculoskelet Disord (2014)

Bottom Line: Rest insertion and increased cycle number also had significant positive effects on the levels of mRNA for TGFB1 and SCXA (p<0.05).There was no direct relation between cell morphology and gene expression, however mechanical stimulation, overall, induced a metabolically active tenocyte phenotype as evidenced by cells that on average demonstrated a decreased major-minor axis ratio (p<0.05) with greater branching (p<0.01).The incorporation of rest periods in a mechanical stretching regimen results in greater collagen type I synthesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, Canada. ascott@interchange.ubc.ca.

ABSTRACT

Background: Mechanical stimulation (e.g. slow heavy loading) has proven beneficial in the rehabilitation of chronic tendinopathy, however the optimal parameters of stimulation have not been experimentally determined. In this study of mechanically stimulated human tenocytes, the influence of rest insertion and cycle number on (1) the protein and mRNA levels of type I and III collagen; (2) the mRNA levels of transforming growth factor beta (TGFB1) and scleraxis (SCXA); and (3) tenocyte morphology, were assessed.

Methods: Human hamstring tenocytes were mechanically stimulated using a Flexcell® system. The stimulation regimens were 1) continuous and 2) rest-inserted cyclic equiaxial strain at a frequency of 0.1 Hz for 100 or 1000 cycles. Data were normalized to unstimulated (non-stretched) control groups for every experimental condition. qPCR was performed to determine relative mRNA levels and quantitative immunocytochemistry image analysis was used to assess protein levels and cell morphology.

Results: Collagen type I mRNA level and pro-collagen protein levels were higher in tenocytes that were subjected to rest-inserted mechanical stimulation, compared to continuous stretching (p<0.05). Rest insertion and increased cycle number also had significant positive effects on the levels of mRNA for TGFB1 and SCXA (p<0.05). There was no direct relation between cell morphology and gene expression, however mechanical stimulation, overall, induced a metabolically active tenocyte phenotype as evidenced by cells that on average demonstrated a decreased major-minor axis ratio (p<0.05) with greater branching (p<0.01).

Conclusions: The incorporation of rest periods in a mechanical stretching regimen results in greater collagen type I synthesis. This knowledge may be beneficial in refining rehabilitation protocols for tendon injury.

Show MeSH

Related in: MedlinePlus

Effect of rest-inserted stretching vs continuous stretching on mRNA expression of collagen type I (A) and III (B) and protein levels of pro-collagen I and III (C). The cells that underwent rest inserted stretching showed an increased mRNA expression of collagen type I (A) at 8 h post stretching (p < 0.05) compared to continuously loaded cells. Collagen type III mRNA expression did not significantly change (B). The pro-collagen type I was significantly greater (p < 0.05) in the rest insertion group compared to the continuously loaded, while the continuous group had an increased (p < 0.05) pro-collagen type III value at 24 hours post stretching (C). The *indicates a significant difference of p < 0.05, the ƚ indicates significant difference of p < 0.01, the error bars indicate the standard error. All data points from each group were normalized to unstretched controls harvested at every time point.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4256895&req=5

Fig1: Effect of rest-inserted stretching vs continuous stretching on mRNA expression of collagen type I (A) and III (B) and protein levels of pro-collagen I and III (C). The cells that underwent rest inserted stretching showed an increased mRNA expression of collagen type I (A) at 8 h post stretching (p < 0.05) compared to continuously loaded cells. Collagen type III mRNA expression did not significantly change (B). The pro-collagen type I was significantly greater (p < 0.05) in the rest insertion group compared to the continuously loaded, while the continuous group had an increased (p < 0.05) pro-collagen type III value at 24 hours post stretching (C). The *indicates a significant difference of p < 0.05, the ƚ indicates significant difference of p < 0.01, the error bars indicate the standard error. All data points from each group were normalized to unstretched controls harvested at every time point.

Mentions: Rest insertion resulted in a greater protein level of pro-collagen type I [1.421(1.399-1.442)] (24 h, p < 0.01) compared to continuous stretching [1.303(1.284-1.322)] while pro-collagen type III levels were greater with continuous stretching [1.223(1.211-1.235)] compared with the cells stretched in the rest-inserted regimen [(1.142(1.130-1.153), 24 h, Figure 1, p < 0.01]. Overall, periods of rest insertion had a positive effect on mRNA levels for collagen type I with a mean difference (CI of difference) of 1.35(1.10-1.65) SCXA 1.30(1.02-1.65) and TGFB1 [1.70(1.10-2.65), 8 h, p < 0.05]. Collagen type I mRNA levels 1.20(1.01-1.43) were increased as early as 4 h (p < 0.05).Figure 1


Enhanced collagen type I synthesis by human tenocytes subjected to periodic in vitro mechanical stimulation.

Huisman E, Lu A, McCormack RG, Scott A - BMC Musculoskelet Disord (2014)

Effect of rest-inserted stretching vs continuous stretching on mRNA expression of collagen type I (A) and III (B) and protein levels of pro-collagen I and III (C). The cells that underwent rest inserted stretching showed an increased mRNA expression of collagen type I (A) at 8 h post stretching (p < 0.05) compared to continuously loaded cells. Collagen type III mRNA expression did not significantly change (B). The pro-collagen type I was significantly greater (p < 0.05) in the rest insertion group compared to the continuously loaded, while the continuous group had an increased (p < 0.05) pro-collagen type III value at 24 hours post stretching (C). The *indicates a significant difference of p < 0.05, the ƚ indicates significant difference of p < 0.01, the error bars indicate the standard error. All data points from each group were normalized to unstretched controls harvested at every time point.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4256895&req=5

Fig1: Effect of rest-inserted stretching vs continuous stretching on mRNA expression of collagen type I (A) and III (B) and protein levels of pro-collagen I and III (C). The cells that underwent rest inserted stretching showed an increased mRNA expression of collagen type I (A) at 8 h post stretching (p < 0.05) compared to continuously loaded cells. Collagen type III mRNA expression did not significantly change (B). The pro-collagen type I was significantly greater (p < 0.05) in the rest insertion group compared to the continuously loaded, while the continuous group had an increased (p < 0.05) pro-collagen type III value at 24 hours post stretching (C). The *indicates a significant difference of p < 0.05, the ƚ indicates significant difference of p < 0.01, the error bars indicate the standard error. All data points from each group were normalized to unstretched controls harvested at every time point.
Mentions: Rest insertion resulted in a greater protein level of pro-collagen type I [1.421(1.399-1.442)] (24 h, p < 0.01) compared to continuous stretching [1.303(1.284-1.322)] while pro-collagen type III levels were greater with continuous stretching [1.223(1.211-1.235)] compared with the cells stretched in the rest-inserted regimen [(1.142(1.130-1.153), 24 h, Figure 1, p < 0.01]. Overall, periods of rest insertion had a positive effect on mRNA levels for collagen type I with a mean difference (CI of difference) of 1.35(1.10-1.65) SCXA 1.30(1.02-1.65) and TGFB1 [1.70(1.10-2.65), 8 h, p < 0.05]. Collagen type I mRNA levels 1.20(1.01-1.43) were increased as early as 4 h (p < 0.05).Figure 1

Bottom Line: Rest insertion and increased cycle number also had significant positive effects on the levels of mRNA for TGFB1 and SCXA (p<0.05).There was no direct relation between cell morphology and gene expression, however mechanical stimulation, overall, induced a metabolically active tenocyte phenotype as evidenced by cells that on average demonstrated a decreased major-minor axis ratio (p<0.05) with greater branching (p<0.01).The incorporation of rest periods in a mechanical stretching regimen results in greater collagen type I synthesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, Canada. ascott@interchange.ubc.ca.

ABSTRACT

Background: Mechanical stimulation (e.g. slow heavy loading) has proven beneficial in the rehabilitation of chronic tendinopathy, however the optimal parameters of stimulation have not been experimentally determined. In this study of mechanically stimulated human tenocytes, the influence of rest insertion and cycle number on (1) the protein and mRNA levels of type I and III collagen; (2) the mRNA levels of transforming growth factor beta (TGFB1) and scleraxis (SCXA); and (3) tenocyte morphology, were assessed.

Methods: Human hamstring tenocytes were mechanically stimulated using a Flexcell® system. The stimulation regimens were 1) continuous and 2) rest-inserted cyclic equiaxial strain at a frequency of 0.1 Hz for 100 or 1000 cycles. Data were normalized to unstimulated (non-stretched) control groups for every experimental condition. qPCR was performed to determine relative mRNA levels and quantitative immunocytochemistry image analysis was used to assess protein levels and cell morphology.

Results: Collagen type I mRNA level and pro-collagen protein levels were higher in tenocytes that were subjected to rest-inserted mechanical stimulation, compared to continuous stretching (p<0.05). Rest insertion and increased cycle number also had significant positive effects on the levels of mRNA for TGFB1 and SCXA (p<0.05). There was no direct relation between cell morphology and gene expression, however mechanical stimulation, overall, induced a metabolically active tenocyte phenotype as evidenced by cells that on average demonstrated a decreased major-minor axis ratio (p<0.05) with greater branching (p<0.01).

Conclusions: The incorporation of rest periods in a mechanical stretching regimen results in greater collagen type I synthesis. This knowledge may be beneficial in refining rehabilitation protocols for tendon injury.

Show MeSH
Related in: MedlinePlus