issue 8 june

Human body parts;natural regeneration or artificial technologyThe possibility of naturally regeneratingdamaged body parts such as the kidney,liver or even heart have put theseorgans on top of the much sought afterorgan-transplant list but some organssuch as the windpipe - which connectsthe nose and mouth to the lungs – orlimbs, are not easy to find.Recently, only the second man-madetrachea implant using synthetic microfibresand a bath of stem cells fromthe bone marrow of a patient whoseown trachea was destroyed by cancer,was performed by a Swedish surgeon.Such techniques represent the futureof regenerative medicine, in which stemcells of all kinds, including those madefrom patients’ own skin cells, can serveas the basis for generating any type ofcell or tissue that needs to be replacedor repaired.Organ transplantation from a donorto a patient’s body has been practisedfor centuries but rejection and theside effects of preventing rejection(especially infection, nephropathy andmedication used to stop rejection) mayalways be the key problem.The body’s immune system usuallyprotects it from substances that maybe harmful such as bacteria, viruses,poisons, and cancer cells. Theseharmful substances have proteins ontheir surfaces called antigens. As soonas these antigens enter the body, theimmune system recognises them asforeign and attacks them. In the sameway, with an organ that is not matchedwith the patient’s cell, antigens cantrigger a blood transfusion reaction ortransplant rejection. Life after organtransplantation is usually a hard oneand even the drugs which suppressthe immune system to stop rejectionhave numerous side effects. That is whyscientists are always looking for newways to reduce or eliminate the rejectionrisk.Stem cells are biologicalcells found in most multicellularorganisms that candivide and differentiate intodifferent specialised celltypes and can self-renew toproduce more stem cells.Stem cells can be grownin vitro (outside the body),in specific lab conditionsand transform into differentbody cells such as muscles,nerves, cartilage in joints,skin, bone tissue and kidney.These cells then can be transplanted tothe human body to repair damaged ordysfunctional organs.Besides the natural regeneration ofbody parts, the technology of makingartificial organs is getting more andmore advanced by the day. A studypublished last April in AdvancedFunctional Materials revealed thatan Iranian team of bioengineers atBrigham and Women’s Hospital (BWH)had created artificial heart tissue thatclosely mimics the functions of naturalheart tissue through the use of humanbasedmaterials.In this method, a rubber like gelmaterial made from a protein which isresponsible for the human tissues’ elasticitywas used to make a high elasticmicro-pattern gel. Dr Nasim Annabi,PhD, BWH-Renal Division, statedthat the micro-patterned gel provideselastic mechanical support of naturalheart muscle tissue as demonstratedby its ability to promote attachment,spreading, alignment, function andcommunication of heart muscle cells.Ali Khademhosseini, PhD, BWH Divisionof Biomedical Engineering, said:“As we continue to move forward withfinding better ways to mend a brokenheart, we hope the biomaterials weengineer will allow us to successfullyaddress the limitations of current artificialtissues.”On the other hand in recent years,thanks to a high-tech quantum leap inproducing false limbs, it has becomepossible for millions of amputees towalk, climb stairs and even compete inhigh-level sports without stress.Computerised bionic prosthetic limbsuse the latest advances in computer,sensor, electric motor and batterytechnology to give the limbs bioniccapabilities. In this technology, sensorsmonitor the user’s motions and use thedata to predict what the person is tryingto do through programmed microprocessors.Last December scientists atthe University of Pittsburgh announcedthat a woman paralysed from the neckdown had been successfully fitted witha robotic hand that can be controlled byher thoughts. In her case two microelectrodearrays were implanted in the leftmotor cortex. These microelectrodeswere conducted to the robotic hand,then after 14 weeks of training shelearned how to use the artificial hand.Future generations will decide whethernaturally regenerated or artificiallymade organs are more useful for humanlife. •Fightingthe killer mosquitoesA prick to the skin, a scratchy redswelling and possibly even a seriousillness, these are the first signs of amosquito attack in which human bloodis sucked up to develop its fertile eggs.When the female mosquito lays eggs, itneeds more protein supplies which canonly be obtained by sucking a host’sblood. When the mosquito sucks bloodit also injects a combination of salivaand anticoagulant compounds intothe blood which may contain infectingelements. However the process ofattraction begins long before thelanding. Mosquitoes can smell theirdinner from an impressive distance ofup to 50 metres.Mosquitoes are important vehiclesin the transmission of some animaldiseases. These small creatures caneasily transmit viruses or parasitesfrom animal to animal, from animalsto people and from person to personwithout being affected by the symptomsof the disease. The insect’s body recognisesthe virus or parasite as a foreignintruder and chops off its geneticcoding, rendering it harmless to itself.Scientists know that genetics accountfor a whopping 85% of our susceptibilityto mosquito bites. They’ve alsoidentified certain elements of our bodychemistry that, when found in excesson the skin’s surface, make mosquitoesflock closer.Fredros Okumu a scientist from theIfakara Health Institute in Tanzania,has designed a mosquito killing trapusing the rancid smell of human feet,collected on sock pads worn by localsoccer players. Okumu who has lostfamily members to malaria, hopes thatif this method is used in tandem withmosquito nets and insect repellents, itwill dramatically reduce the number ofmosquito bites.In another attempt to combat thesekiller mosquitoes, scientists around theworld have tried genetic engineeringoptions. A British biotechnologycompany has found a way to geneticallymanipulate Aedes aegypti, themosquito species mainly responsiblefor transmitting dengue and yellowfever viruses. The mosquitoes had beengenetically modified to be sterile, sothat when they mated with the indigenousfemale mosquitoes there wouldbe no offspring. The company releasedmillions of mutant mosquitoes into a40-acre area of the Cayman Islands, 3times a week from May to October 2010.By August the same year the populationof mosquitoes had dropped by 80%.Australian scientists, meanwhile, havedeveloped a new strategy involving useof a bacterium which naturally infectsmany insect species and has the abilityto interfere with its host’s reproductivecharacterisation. When mosquitoes areinfected by these bacteria, their abilityto transmit dengue virus is almostcompletely blocked.Mosquito borne diseases like malaria,dengue and West Nile, kill more peoplethan any other disease in the worldand more than 700 million are affectedworldwide. Nearly a million people diefrom malaria each year, of which morethan 85% happen to be in Africa: thisequates to one fatality every 30 seconds.A large parasite prevalence surveyshowed that out 1.38 billion people atrisk of stable malaria, 0.69 billion werefound in Central and South East Asia,0.66 billion in Africa, Yemen, and SaudiArabia, and 0.04 billion in the Americas.This means that a large portion of theMuslim population worldwide is at riskof being affected by this deadly disease.Some Islamic organisations have beenhelping to control mosquito bornediseases in Africa and Asia. They havemanaged to launch malaria treatmentand prevention projects focussing onpregnant women and children underfive. Their aim is to reduce the rate ofinfant mortality and decrease malariaand anaemia cases among pregnantwomen in regions such as the BlueNile State of Sudan, the Afder zoneof Ethiopia and the Warrap region ofKenya.In the meantime the challenge forscientists is also to find similar low riskways of controlling malaria. •Dr Laleh Lohrasbi isa pharmacologist. Shehas worked as an editorfor the medical sectionof “Hamshahri”, a dailynewspaper in Tehran.6061