Influence of Glycerol on the Mechanical Reversibility and Thermal Damage Susceptibility of Collagenous Tissues

Abstract

Clinical procedures wherein supraphysiologic temperatures must be achieved in deep layers of tissue via light are often compromised by optical scattering and absorption. Optical clearing of tissue superficial to the target improves the efficacy of such procedures. Glycerol is an attractive chemical agent for achieving dramatic reductions in tissue turbidity, but its net effects on healthy tissue are not fully understood. In this paper, we investigate possible alterations of biaxial mechanical properties in a model collagenous tissue, bovine epicardium, induced by glycerol. Furthermore, we examine the effects of glycerol on the biaxial thermomechanical properties of epicardium constrained at near-physiologic length. It is seen that mechanical changes induced by glycerol are fully reversed upon rehydration in normal saline. Moreover, glycerol protects cleared tissue by increasing its thermal stability and minimizing thermal alterations of mechanical properties.

Quantification of glucose and glycerol diffusion in myocardium

“…[36][37][38][39][40][41] We have found that only in two papers optical clearing of heart tissues were investigated. 42,43 Authors of Ref. 42 have studied the in°uence of a highly concentrated glycerol on the optical clearing, mechanical reversibility, and thermal damage susceptibility of myocardium and epicardium, and authors of Ref.…”

“…42,43 Authors of Ref. 42 have studied the in°uence of a highly concentrated glycerol on the optical clearing, mechanical reversibility, and thermal damage susceptibility of myocardium and epicardium, and authors of Ref. 43 used a mineral oil/glycerol mixture for optical clearing of archive-compatible para±n embedded mouse tissues of many types, including heart tissue, with the aim of multiphoton microscopy.…”

“…In spite of the more or less intensive studies of optical clearing e±ciency of skeletal muscle [36][37][38][39][40][41] and a few studies on cardiovascular muscle tissue, 42,43 di®usion coe±cients neither for glucose nor glycerol in the myocardium have not been measured yet. The knowledge of di®usion coe±cients for OCA-water°u xes in tissues allows one to understand the optical clearing mechanisms more precisely, to improve the mathematical models describing the interaction of the OCAs with the tissue.…”

Correlation between collagen solubility and skin optical clearing using sugars

“…Optical clearing can be dramatic as tissue becomes visibly transparent and loses mechanical compliance. This process is reversible when upon subsequent immersion in isotonic saline, tissue turbidity, and mechanical properties return to their native states [7]. These ''clearing'' agents are benign, biocompatible and already in use as sweetening additives in foods and emollients in skin care products.…”

Single point and imaging measurements of the optical clearing process

“…This refractive index matching greatly reduces the scattering in the tissue. This process is reversible when upon subsequent immersion in isotonic saline tissue optical and mechanical properties return to their native states [9] One issue with the use of optical clearing agents is that they also affect the functions of the tissue. They have been reported to lead to temporal local stasis in some blood microvessels of skin [11].…”