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Wounds heal with­out scars while bears hibernate

pub­lished 25 March 2012 | mod­i­fied 07 April 2012

Black bears have a sur­pris­ing capac­ity to heal as they hiber­nate, say researchers in the US. Med­ical researchers and zool­o­gists worked together to find that the bears’ wounds healed with almost no scar­ring, and were infection-​free.

The sci­en­tists hope, even­tu­ally, to find out exactly how the bears’ bod­ies heal while their body tem­per­a­ture, heart rate and metab­o­lism are reduced. This could aid stud­ies of human wound-​healing.

The team has been track­ing and mon­i­tor­ing black bears in Min­nesota for 25 years. The find­ings, pub­lished in the jour­nal Inte­gra­tive Zool­ogy, are of par­tic­u­lar rel­e­vance to med­ical researchers hop­ing to improve slow-​healing and infection-​prone wounds in elderly, mal­nour­ished or dia­betic patients.

This study was part of a project by sci­en­tists from the uni­ver­si­ties of Min­nesota, Wyoming and the Min­nesota Depart­ment of Nat­ural Resources, who have tracked 1,000 black bears, in order to mon­i­tor their health and behav­iour, for 25 years. Whilst track­ing the bears — using radio col­lars — the researchers noticed some early evi­dence of their sur­pris­ing heal­ing abilities.

We con­sider this to have impli­ca­tions for med­ical research. If we can work out how the bears heal, we hope there’ll be poten­tial to trans­late this research to stud­ies of human healing

black bear

They wrote in their paper: “We iden­ti­fied a few ani­mals each year with injuries result­ing from gun­shots or arrows from hunters; bite marks from other bears or preda­tors. “These wounds were con­sid­ered to have been incurred some time before the bears denned, and were often infected or inflamed… in early win­ter. “Yet typ­i­cally, when we revis­ited bears in their dens a few months later, most wounds had com­pletely resolved whether or not we cleaned them, sutured the areas or admin­is­tered antibiotics.”

To test the bear’s heal­ing abil­i­ties exper­i­men­tally, the team care­fully tracked the heal­ing of small cuts on the skin of 14 of their radio-​collared bears in north­ern Min­nesota. Between Novem­ber (when the bears first set­tled down in their dens) and March (about a month before they emerged) the wounds healed with “min­i­mal evi­dence of scar­ring”. Added to this, there were no signs of infec­tion, the lay­ers of dam­aged skin regrew and many of the bears even grew hair from newly formed fol­li­cles at the site of their injuries.

One of the researchers, Prof David Garshe­lis from the Uni­ver­sity of Min­nesota, told BBC Nature: “It seems so sur­pris­ing to us that their wounds would heal so well and so com­pletely when they’re hiber­nat­ing and their metab­o­lism is slowed down.” But, he added, “the ani­mals had many other remark­able adap­ta­tions to hiber­na­tion. They sit in the den for six months and don’t lose any appre­cia­ble mus­cle or bone mass, so I guess this heal­ing is another adaptation.”

Dur­ing its win­ter hiber­na­tion, a black bear’s core body tem­per­a­ture is reduced by as much as 7°C and their heart rate low­ers dra­mat­i­cally. In humans, a low­ered body tem­per­a­ture, or con­di­tions that ham­per cir­cu­la­tion can seri­ously com­pli­cate wound-​healing. For this rea­son, the team hope to find out the mech­a­nism behind the bears’ remark­able heal­ing abil­i­ties. This could be espe­cially impor­tant for the devel­op­ment of treat­ments for slow-​healing skin wounds in mal­nour­ished, hypother­mic, dia­betic and elderly patients.

The above news item is reprinted from mate­ri­als avail­able at web­site BBC Nature News. Orig­i­nal text may be edited for con­tent and length.

(Source: BBC Nature News, 19.03.2012)

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