Heat shock proteins 47 and 70 expression in rodent skin model as a function of contact cooling temperature: Are we overcooling our target?
OBJECTIVE
The degree of protective cooling required during laser therapy to achieve an optimal result is unknown. The expression of heat shock proteins, Hsp47 and Hsp70, were examined in the epidermis and dermis as biomarkers to quantify the degree and depth of tissue affected by non-ablative laser treatment using variable protective cooling parameters.


METHODS
Twenty-one male Sprague-Dawley rats were treated with a 1,319 nm Nd:YAG laser using a sapphire cooling plate attached to the hand piece. A 4 cmx4 cm area on each side of the rat was treated with the same energy and pulse settings, with variable contact cooling. Protective cooling parameters, for each degree increment, ranging from 0 to 25 degrees C were studied. Immunohistochemistry (IHC), Western blot and PCR were performed to evaluate the effects of superficial cooling on Hsp47, and Hsp70 expressions.


RESULTS
Our data showed the extent of topical cooling needed to produce a thermal effect at different depths in the dermis, quantified by the expression of Hsp47 and Hsp70. Significant Hsp expression was observed with cooling of 13 degrees C and warmer; no identifiable cellular reaction was observed when cooling below 5 degrees C. There was no evidence of epidermal injury when treating the skin with any protective cooling ranging from 0 to 25 degrees C.


CONCLUSIONS
Our data would suggest contact cooling temperatures 5 degrees C and below completely protects through the entire dermis. There was no evidence of epidermal injury with protective cooling at any temperature between 0 and 25 degrees C. Warmer temperatures are safe and adequately protect the epidermis in this model.
Department of Plastic Surgery, Clinical Center for Cosmetic Laser Treatment, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas, Texas 75390-8650, USA.
Spencer A
SA
Brown
Jordan P
JP
Farkas
Christopher
C
Arnold
Daniel A
DA
Hatef
Jane
J
Kim
John
J
Hoopman
Jeffrey M
JM
Kenkel
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D003080:Cold Temperature; D062109:Dermatologic Surgical Procedures; D050958:HSP47 Heat-Shock Proteins / Q000032:analysis / Q000096:biosynthesis*; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis / Q000096:biosynthesis*; D007036:Hypothermia, Induced; D053685:Laser Therapy; D008297:Male; D023421:Models, Animal; D051381:Rats; D012867:Skin / Q000473:pathology; D012881:Skin Temperature / Q000502:physiology
D015415:Biomarkers; D050958:HSP47 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins