Comparing the effects of Dextran 70 and Hydroxyethyl starch in an intestinal storage solution.
BACKGROUND
Our lab has developed a novel strategy for intestinal preservation involving the intraluminal delivery of a nutrient-rich preservation solution. The aim of this study was to compare the effectiveness of two impermeant agents for use in our solution: Dextran 70 (D70; Mw=70 kDa) and Hydroxyethyl starch (HES; Mw=2200 kDa).


METHODS
Rat intestines were procured, including an intravascular flush with University of Wisconsin solution followed by a 'backtable' intraluminal flush with: UW solution (group 1, UW), or an amino acid-based nutrient-rich preservation solution (AA solution) containing either 5% D70 (group 2, AA-D70) or HES (group 3, AA-HES). Tissue samples (n=6) were taken at 2, 4, 8, and 12 h cold storage; histology, energetic, end-product, and oxidative parameters were assessed. In separate groups (n=4), D70 and HES were fluorescently labeled with fluorescein isothiocyanate (FITC) in order to directly observe mucosal penetration of the starch and dextran.


RESULTS
Over the 12 h storage time-course, direct visualization of the fluorescently labeled D70 showed penetration of the mucosal layer as early as 2 h and progressively continued to do so throughout the 12 h period. In contrast, HES did not cross the mucosal barrier and remained captive within the lumen. As time of storage progressed, grade of injury increased in all groups, however, at 4 and 12 h the AA-HES treated tissues exhibited significantly less injury compared to UW and AA-D70, P < 0.05. AA-HES group showed on moderate villus clefting (median grade 2; P < 0.05) while the AA-D70 group exhibited complete villus denudation (grade 4) and the UW group had extensive injury into the regenerative cryptal regions (grade 6). Metabolic parameters revealed a preferential maintenance of ATP and Energy Charge; increases in lactate, alanine and ammonium supported the involvement of aerobic and anaerobic pathways for energy production.


CONCLUSIONS
The results of this study challenge the idea that oncotic support is not a fundamental requirement of static organ storage. Furthermore, our data suggests that HES is an effective oncotic agent for use in our intraluminal nutrient-rich preservation solution, while Dextran 70 is not.
Kokotilo
Matthew S
MS
Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.
Schlachter
Kimberly
K
Carter
Jodi
J
Thiesen
Aducio
A
Khadaroo
Rachel G
RG
Churchill
Thomas A
TA
D000241:Adenosine / Q000494:pharmacology; D000493:Allopurinol / Q000494:pharmacology; D000818:Animals; D003911:Dextrans / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects; D005978:Glutathione / Q000494:pharmacology; D006895:Hydroxyethyl Starch Derivatives / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009926:Organ Preservation / Q000379:methods; D019188:Organ Preservation Solutions / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D011887:Raffinose / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D003911:Dextrans; D006895:Hydroxyethyl Starch Derivatives; D007328:Insulin; D019188:Organ Preservation Solutions; C055206:University of Wisconsin-lactobionate solution; D000493:Allopurinol; D005978:Glutathione; D000241:Adenosine; D011887:Raffinose