Navigation Links
Researchers explore new driver of transplant rejection: Platelets
Date:2/17/2009

Platelets, tiny and relatively uncharted tenants of the bloodstream known mostly for their role in blood clotting, turn out to also rally sustained immune system inflammatory responses that play a critical role in organ transplant rejection, according to a new report from Johns Hopkins scientists.

"Platelets potentially hold sway over many aspects of transplant biology," says Craig Morrell, D.V.M., Ph.D., an assistant professor of molecular and comparative pathobiology at the Johns Hopkins University School of Medicine. "Our data, as well as others', show a surprising interplay of platelets and the immune system, so it's time for the transplant world at large to have platelets on its radar."

A self-described "platelet guy" transfixed by the unexplored biology of these circulating bodies, Morrell collaborated with clinicians in the fields of transplant to write a comprehensive review of platelets and transplant biology, published in the January issue of the American Journal of Transplantation.

"It all began with the observation that when transplant tissue is rejected, platelets line up in the interior of blood vessels feeding the tissue," Morrell says. "It turns out they are not just bystanders, but have a role in driving that rejection."

As one of the most abundant cell types in the blood second only to the oxygen-carrying red variety platelets are ubiquitous but relatively unexplored, Morrell says. "It's crazy how many potentially active molecules are jam-packed in these small cells and that we're only just beginning to appreciate their pro-inflammatory qualities."

In fact, mounting evidence from Morrell and others shows that platelets are part of a sustained and general immune response that can trigger or exacerbate organ rejection. Not only do they rush to the scene of a wound and adhere to local blood vessels, preventing fatal bleeding, they also dump out granules that "talk to" immune system white blood cells, Morrell says, recruiting them from far and wide to stave off potential infections.

These are on the whole very good things for platelets to do, Morrell says, but in the context of organ transplants, their pro-inflammatory function gets out of control, and they do more bad than good after contributing to initial wound healing.

Strategies using drugs or other means to keep platelets quiet and non-inflammatory might benefit transplant patients in the long run because chronic rejection as contrasted with acute or immediate organ rejection is a major complication for which there is little current treatment, according to Hamid Rabb, M.D., medical director of kidney transplantation and a professor of medicine at the Johns Hopkins University School of Medicine.

In prior research using mice with skin transplants, Morrell and his team noted that increased platelet interactions led to increased and prolonged white cell interactions with the inner lining of the blood vessels and worsened transplant vessel damage.

"We watched platelets flowing through the blood vessels of transplanted skin in mice with and without platelets and determined tissue-platelet interactions by comparing the speeds of those flows," says Morrell, whose team ultimately demonstrated that antibodies made in reaction to the transplanted tissue sparked platelet activation and white cell recruitment.

Studies on tissue from platelet-depleted mice helped confirm the importance of platelets in white cell activation and recruitment, strongly suggesting that limiting the inflammatory response might improve transplanted tissue survival.

Mounting evidence suggesting that platelets are activated not only post-transplant, but also during organ harvest, presents new opportunities for attacking organ injury and rejection head-on, says Rabb. The traditional target of current anti-rejection medicine is the so-called T lymphocyte a white blood cell believed to be the major orchestrator of the immune response against any foreign tissues, including transplants.

"The thought was that if we hit the general that initiates acute rejection, it would put the troops in disarray," says Rabb. "Traditional therapies therefore inhibit or deplete T lymphocytes and other white blood cell components of the immune system. The newest kid on the block is the platelet and it represents an opportunity to target the effectors of organ injury rather than only the general."


'/>"/>

Contact: Maryalice Yakutchik
myakutc1@jhmi.edu
443-287-2251
Johns Hopkins Medical Institutions
Source:Eurekalert

Related biology news :

1. Forget the antioxidants? McGill researchers cast doubt on role of free radicals in aging
2. Researchers isolate protein domain linked to tumor progression
3. CSHL researchers identify gene that helps plant cells keep communication channels open
4. Researchers identify gene linked to aggressive progression of liver cancer
5. Case Western Reserve researchers looking at light-induced toxins in air and water
6. McMaster researchers discover new mode of how diseases evolve
7. Researchers shed new light on connection between brain and loneliness
8. Texas researchers provide emissions data for livestock industry
9. Biodiversity itself begets a species cascade, researchers say
10. NYU Langone Medical Center researchers find micro RNA plays a key role in melanoma metastasis
11. While focusing on heart disease, researchers discover new tactic against fatal muscular dystrophy
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/8/2016)... Research Future published a half cooked research report on Mobile Biometric ... Market is expected to grow over the CAGR of ~35% during ... ... Mobile Biometric Security and Service Market is increasing at a ... security from unwanted cyber threats. The increasing use of mobile device ...
(Date:12/8/2016)... , Dec. 8, 2016  Singulex, Inc., the ... Counting technology, entered into a license and supply agreement ... science. The agreement provides Singulex access to Thermo Scientific ... Europe is used to diagnose systemic bacterial ... States to aid in assessing the risk ...
(Date:12/7/2016)... According to a new market research report "Emotion Detection and Recognition Market ... Application Area, End User, And Region - Global Forecast to 2021", published by ... 2016 to USD 36.07 Billion by 2021, at a Compound Annual Growth Rate ... ... MarketsandMarkets Logo ...
Breaking Biology News(10 mins):
(Date:12/8/2016)... DIEGO , Dec. 8, 2016  Biotheranostics ... demonstrating the role of the Breast Cancer Index ... ER+ breast cancer are most at-risk for disease ... Data include results from three studies advancing the ... information related to tumor biology and inform decisions ...
(Date:12/8/2016)... DIEGO , Dec. 8, 2016  Renova™ ... for congestive heart failure and type 2 diabetes, ... for a novel adeno-associated virus (AAV) vector developed ... , M.D., Ph.D., at Stanford University. The company ... its paracrine gene therapy product pipeline. ...
(Date:12/8/2016)... Dec. 8, 2016 Eurofins announces the appointment of ... of Eurofins Scientific Inc. (ESI). Mr. Murray will ... professional and entrepreneurial experience in leading international business teams. As the ... testing market to uphold Eurofins, status as the global leader in ... , ...
(Date:12/8/2016)... ... December 08, 2016 , ... ... cells — optogenetics — is key to exciting advances in the study and ... patterned light projected via free-space optics stimulates small, transparent organisms and excites neurons ...
Breaking Biology Technology: