|
Sign In to gain access to subscriptions and/or personal tools.
|
Scaffold and Growth Factor Selection in Temporomandibular Joint Disc Engineering
K.D. Allen and
K.A. Athanasiou*
Department of Bioengineering, Rice University, MS-142, PO Box 1892, Houston, TX 77251-1892, USA
View larger version (44K):
[in this window]
[in a new window]
|
Figure 1. Comparisons of PLLA and PGA scaffolds for TMJ disc tissue engineering. Approximately 150,000 cells were seeded to either poly-L-lactic acid (PLLA) or polyglycolic acid (PGA) scaffolds and cultured for 4 wks. Weeks 0 and 4 properties are displayed in mean ± standard deviation form, and statistical differences are denoted by asterisks (p < 0.05). (A) PGA scaffolds contracted rapidly over 4 wks. By week 4, PGA constructs experienced at least a 90% reduction in volume; PLLA construct volume change was negligible. (B) Cellular, collagen, and glycosaminoglycan (GAG) properties of PLLA and PGA constructs were similar at weeks 0 and 4. GAG content of PGA constructs decreased from week 0 to week 4; this was also observed on a per cell basis. Collagen content at week 0 appeared higher on PGA; this difference was substantially less at week 4, since collagen per cell appeared to rise on PLLA. However, collagen differences were not statistically significant. (C) Under compression, week 0 PGA constructs had higher viscosity than PLLA constructs at either week 0 or week 4. PLLA constructs had larger relaxation moduli relative to PGA at week 0. Under tension, PLLA constructs were significantly stiffer and stronger than week 0 PGA constructs. Though PGA and PLLA entered seeding with similar tensile stiffness (unseeded, dry), PGA constructs lost considerable tensile stiffness during the seeding period. By week 4, PGA constructs were no longer testable under compression or tension, while PLLA constructs maintained testability and similar tensile properties.
|
|
View larger version (26K):
[in this window]
[in a new window]
|
Figure 2. Biochemical properties of constructs exposed to IGF-I, TGF-β1, TGF-β3, or no additional growth factor. Construct biochemical properties are displayed in mean ± standard deviation form, and pre-treatment level is marked by a solid line (n = 5). Statistical differences between a treatment group and pre-treatment controls are marked by asterisks (p < 0.05). Differences among treatment groups at a specific time-point are denoted by letters. The absence of marking denotes that the treatment group did not statistically differ from other treatments. (A) Construct cellularity of ’no treatment’ and IGF-I dropped from weeks 0 to 3. Week 3 TGF-β1 and TGF-β3 samples had cellularity similar to that of pre-treatment controls. At week 6, all constructs had higher cellularity relative to pre-treatment controls. TGF-β1 had the largest effect on cellularity at week 6 ( ), statistically outperforming all other constructs. Week 6 TGF-β3 samples also showed large effects (β), statistically outperforming IGF-I and ’no treatment’ samples ( ). (B) Collagen content was similar among all week 3 samples and pre-treatment controls. At week 6, samples treated with TGF-β1 () had more collagen deposition than all other samples. Week 6 TGF-β3 (β) samples had more collagen than week 6 IGF-I and ’no treatment’ samples (). On a per cell basis, TGF-β1 and TGF-β3 (a) outperformed IGF-I and ’no treatment’ (b) at week 6. TGF-β1 and TGF-β3 samples appeared to sustain collagen production levels per cell, while IGF-I and ’no treatment’ samples appeared to drop below pre-treatment levels. However, this observation is not statistically significant. (C) Week 3 IGF-I and ’no treatment’ samples had less GAG than pre-treatment controls; by week 6, IGF-I and ’no treatment’ samples rebounded to pre-treatment levels. Week 3 TGF-β1 and TGF-β3 samples maintained similar GAG content relative to pre-treatment levels. At week 3, TGF-β1 samples (A) had significantly more GAG than IGF-I (B). At week 6, TGF-β1 () samples were outperforming all other treatments (p < 0.05). Week 6 TGF-β3 samples (β) had higher GAG content than week 6 IGF-I and ’no treatment’ samples (). On a per cell basis, IGF-I and ’no treatment’ samples (a) outperformed TGF-β3 (β) at week 3. By week 6, no differences existed among treatments on a per cell basis, though all were well below pre-treatment and week 3 levels.
|
|
View larger version (23K):
[in this window]
[in a new window]
|
Figure 3. Biomechanical properties of constructs exposed to IGF-I, TGF- β 1, TGF-β 3, or no additional growth factor. Construct mechanical properties are displayed in mean ± standard deviation form, and statistical differences are denoted by an asterisk (p < 0.05). Statistical differences in compressive properties were limited to the coefficient of viscosity. Week 6 TGF-β 1 samples had significantly larger coefficients of viscosity than week 6 ’no treatment’ samples, but did not differ from other week 6 treatments or pre-treatment levels. Statistical differences in tensile properties were limited to the tensile modulus. The tensile stiffness increased in TGF-β 1-treated constructs, with week 6 TGF-β 1 constructs having significantly larger moduli than pre-treatment controls. All week 6 samples appeared to increase slightly in stiffness relative to unseeded, non-wetted mesh.
|
|
View larger version (44K):
[in this window]
[in a new window]
|
Figure 4. Total collagen staining and gross appearance of constructs exposed to IGF-I, TGF-β 1, TGF-β 3, or no additional growth factor. Collagen staining (marked by white arrows) was faint and sparse at week 0 (10x photo). Significant improvement in total collagen deposition was not observed in any treatment at week 3 (10x photo). Staining remained sparse and faint, generally located around the periphery of the scaffold. At week 6, constructs treated with TGF-β 1 or TGF-β 3 appeared to be denser (gross appearance – 4x photo). Collagen staining verified this observation. TGF-β 1-treated constructs showed significant staining for collagen relative to other treatments (10x photos). Staining was darkest around the periphery of the scaffold, followed by the pin-sized hole near the center of the scaffold created by the spinner flask mounting wire. Collagen staining in the interior of the constructs was less intense and non-continuous. TGF-β 1- and TGF-β 3-treated constructs were the only samples to exhibit any staining in the interior portions of the scaffold.
|
|
Journal of Dental Research, Vol. 87, No. 2,
180-185 (2008)
DOI: 10.1177/154405910808700205
 CiteULike  Complore  Connotea  Del.icio.us  Digg  Reddit  Technorati  Twitter What's this?
|
|
