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Swelling of Collagen-Hyaluronic Acid Co-Gels: An In Vitro Residual Stress Model.

ABSTRACT: Tissue-equivalents (TEs), simple model tissues with tunable properties, have been used to explore many features of biological soft tissues. Absent in most formulations however, is the residual stress that arises due to interactions among components with different unloaded levels of stress, which has an important functional role in many biological tissues. To create a pre-stressed model system, co-gels were fabricated from a combination of hyaluronic acid (HA) and reconstituted Type-I collagen (Col). When placed in solutions of varying osmolarity, HA-Col co-gels swell as the HA imbibes water, which in turn stretches (and stresses) the collagen network. In this way, co-gels with residual stress (i.e., collagen fibers in tension and HA in compression) were fabricated. When the three gel types tested here were immersed in hypotonic solutions, pure HA gels swelled the most, followed by HA-Col co-gels; no swelling was observed in pure collagen gels. The greatest swelling rates and swelling ratios occurred in the lowest salt concentration solutions. Tension on the collagen component of HA-Col co-gels was calculated from a stress balance and increased nonlinearly as swelling increased. The swelling experiment results were in good agreement with the stress predicted by a fibril network + non-fibrillar interstitial matrix computational model.

SUBMITTER: Lai VK

PROVIDER: S-EPMC5045778 | biostudies-other | 2016 Oct

REPOSITORIES: biostudies-other

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Swelling of Collagen-Hyaluronic Acid Co-Gels: An In Vitro Residual Stress Model.

Lai Victor K VK Nedrelow David S DS Lake Spencer P SP Kim Bumjun B Weiss Emily M EM Tranquillo Robert T RT Barocas Victor H VH

Annals of biomedical engineering 20160505 10

Tissue-equivalents (TEs), simple model tissues with tunable properties, have been used to explore many features of biological soft tissues. Absent in most formulations however, is the residual stress that arises due to interactions among components with different unloaded levels of stress, which has an important functional role in many biological tissues. To create a pre-stressed model system, co-gels were fabricated from a combination of hyaluronic acid (HA) and reconstituted Type-I collagen (C ...[more]

PMID: 27150674

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Project description:IntroductionViscosupplementation by intra-articular injection of hyaluronic acid (HA) is a widely used treatment for lower limb osteoarthritis. However, the injected HA is rapidly degraded by reactive oxygen species (ROS), limiting its time of intra-articular residence. Optimizing clinical effectiveness of viscosupplementation by reducing HA degradation in situ, and therefore increasing the time of contact with the diseased tissue, is a challenging research approach. Mannitol, a powerful ROS scavenger, is a good candidate for this. The aim of this study was to compare in vitro the resistance to ROS-mediated degradation of two marketed viscosupplements (one linear and one cross-linked) to that of two novel viscosupplements combining HA and mannitol.MethodsA HA viscosupplement at a concentration of 10 g/L (HA 1%), was compared to a HANOX-M, a novel viscosupplement made of a mixture of HA and mannitol. In a second experiment, Hylan G-F 20, a partially cross-linked viscosupplement, was compared to a HANOX-M-XL, a novel cross-linked viscosupplement made of a HA and mannitol (35 g/L). The four HA viscosupplements were subjected to oxidative stress generated by the addition of hydrogen peroxide (H2O2) and their rheological behavior (elastic moduli [G'], viscous moduli [G″], and complex viscosity [|η*|]) were compared before and after the oxidative stress exposure.ResultsThe two viscosupplements not containing mannitol HA were rapidly degraded by H2O2, as demonstrated by the dramatic decrease of |η*|. On the other hand, the rheological properties of HA containing mannitol were not substantially modified in the presence of H2O2.ConclusionThis in vitro study demonstrates that mixing mannitol with HA protects the viscosupplement from ROS-mediated degradation and might therefore increase its intra-articular residence time without substantially modifying its rheological behavior. This in vitro study has to be followed by clinical trials designed to assess whether the addition of mannitol to HA might improve the efficiency and/or the duration of action of viscosupplementation.

Project description:During the last years, several attempts have been accomplished to improve the wound healing. Device application aimed at enhancing skin ability to reconstruct its damaged sites through a proper dermal regenerative process. In particular, Q-switched Nd-YAG laser (Medlite C6 laser, Conbio, USA) applied with a fluence of 8 J/cm2, a pulse width of 5 ns, and a spot size of 4 mm exerts a photo-mechanical action that improve skin repair. Besides, hyaluronan hybrid cooperative complexes (HCC) widely exploited in dermoesthetic applications proved specific actions on keratinocytes and fibroblasts monolayer repair. We evaluated this specific laser treatment in vitro on a wound healing model based on human keratinocytes (HaCaT) alone and in combination with HCC. In addition, we evaluated key biomarkers of dermal repair. Scratched HaCaT monolayers were treated with laser and successively with HA-based formulations (HHA and HCC). For each treatment and the control samples, at least 3 different wells were analyzed. Wound closure was quantified, measuring five view filed for each well at increasing incubation time, exploiting time lapse videomicroscopy and image analysis, permitting to compare the different healing rate of treatments respect to control. By real-time PCR and western blotting, we evaluated biomarkers of wound regeneration, such as integrins, aquaporin three (AQP3), and proinflammatory cytokines. The ANOVA test was used to assess statistical significance of the results obtained. Laser-treated cells achieved wound closure in about 37 h, faster than the control, while when coupled to HCC, the complete reparation was obtained in 24 h. Integrin αV was upregulated by treatments, with in particular about four-fold increase respect to the control when HCC + laser was used. In addition, integrin β3 was upregulated by all treatments especially with the combination of laser and HCC proved more efficient than others (~ 14-folds). A slighter but significant increase of AQP3 gene expression of 61% was found for laser treatment while the latter combined with HCC determined an upregulation of 72%. By coupling laser treatment and HCC, further healing improvement and consistent biomarker modulation was observed. Our results may support clinical implementation of new dermatology protocols conjugating laser treatments with topical or injective HA formulations as a valid tool in treatments to repair scars or other skin defects.

Dataset Information

Swelling of Collagen-Hyaluronic Acid Co-Gels: An In Vitro Residual Stress Model.

Publications

Swelling of Collagen-Hyaluronic Acid Co-Gels: An In Vitro Residual Stress Model.

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