Autografts vs Xenografts vs Allografts

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background

Synthetic scaffold have been used for a long period of time For tissue replacement. However their low biocompatibility property had promote many tissue degradation and rejection upon surgical procedure. Biological scaffold are widely used now days for tissue replacement.They are defiend as decelluralize extracellular matrix made of laminin, fibrinectin,elastin and collagen.Among their applicatin are skin replacement,Hernia repair,breast reconstruction,tendon repair and gencological reconstruction. and the replacement of other tissue around the body.Thre type of biological scaffold exist, Those include Autograft,Xenograft and Allograft.Each of them differ in their biocomapatibilty,source of the grafts,on how their cross to the host tissue, importantly on their regulation by the FDA.In 1823 the first skin graft-transplantation from one location of an individual to another location was performed successfully.However, it wasin the early twentieh century that xenograft was first performed.In additon the first allograft was performed in 1837 in a gazelle.In this paper, we will compare and contrast those three biological scaffold.

History

-1823- First autograft was performed -1837-First allograft on a gazelle

Allografts,Xenografts,Autografts(source comparison)

Grafts is performed as a medical procedure to repair a damage tissue. Three different type of graft exist depending on their sources .those include xenografs, Autografts and allografts. Xenografts is defined as the transplantation of tissue from one donor to a completely different species(animal to human)An example are the small intestine and dermis of the porcine,pericardium,fetal and dermis of of a bovine and also equine.However,xenografts originating from country which has an history of spongiform encephalopathy are forbidden. Their differ from the allografts in which case the donor and the host are from the same species( human to human).In Autografts,The recipient is consider as the source in which case a tissu is transplanted from one part of the body to another.

Xenografts,allografts,autografts(preparation procedure)

A perfect grafts can be define as biocompatible to the host environment,supprot tissu repair,conatin noantigen which could promote an acute immun respoense.Therfore,the preparation of each before implatation is a very important are reagulated by the FDA(Food and Drug Administration). Prior implation the donnor is tested for anytype of atigen such us HIV1,HIV2,hepatitis B and C,trace of toxics substance as reqired by the FDA.However,due high degree of genetic identity between the host and the donnor in allograft and autogratf less test are required.After the obtention of the graft,the donnor tissue is decellurized,disinfected and packeged( autograft and allograft) by a tissu bank recognized by the FDA.However in 2002,the center for disease control( CDC)identify of clostridium antigen on 13 and 11 of them originated from the same.This issue downsocre the importance of the FDA requirementfor donnors creening.Decelurization also occur with the xenografts after which we have coss linking of the scaffold and sterilization.

Clinical comparison

As we know, tissue repair are suported by fibroblast penetration,acellularization and remoddeling.Fibroblast penetration in the site of grft is very important for tissue healingin the sense that it promote acellurization. Autograft and Allograft promote more infiltration of fibroblast compare to xenograth. This is due to the excessive cross link of the scaffold.Experiment perfom on a human acellurized dermal matrix and porcine dermal matrix confirm a large amount of fibroblast at the site of grafts compare to bovine in wich a large amount of fibroblast was found at a later time..Would healing also occurs slowly in xenograft comapre to allograft and autograft. Different studies suggest that the crosslinking of the scaffold in xenograft reduce their permeability to the fibrblast which in turn slow the series require for proper wound healing.Remodelling occur after fibroblast penetration and acellurization. During this stage,the newly impalnt graft try accomodate to the new enviroment.If remodelling doesnt occur properly,tissue degradion and rejection could occur.

Regulation

Tissue implantation are regulated by the FDA.However the regulation differ for each biological scaffold. Xenografts are considered as medical devices while autografts and allografts are viewed as a Human Cell and Tissue/Product by the FDA.I addition, due to the high degree of biocompatibilty, allograft and autograft are sterilize before implantation compare to xenograft.In addition, the requirement for packaging and storage are by the tissue bank.

references

<<https://cme.ucsd.edu/biologicscaffolds/AllograftvsXenograftMonograph.pdf>>[1] <<>>[2] <<>> <<>> <<m>>[4] <<https://biologywarakwarak.wordpress.com/2012/03/18/role-and-components-of-the-immune-response/>> <<d>>[5]