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Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
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Home | Pregnancy Timeline | News Alerts |News Archive Sept 5, 2014

A working thymus is an important organ which supplies the body with immune cells.

Left: Specialised thymus cells were created in the lab from a completely different cell type.
Right: Thymus cells were transplanted onto a mouse kidney and formed an organised and functional mini-thymus in a living mouse.
Image Credit: MRC Centre for Regenerative Medicine, University of Edinburgh

 






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Thymus organ grown from cells in a lab

Laboratory-grown replacement organs have moved a step closer with the completion of a new study where scientists have grown a fully functional organ from transplanted laboratory-created cells and placed it in a living mouse.

The researchers have created a thymus - an organ next to the heart that produces immune cells known as T cells that are vital for guarding against disease. They hope that, with further research, the discovery could lead to new treatments for people with a weakened immune system. The team from the MRC Centre for Regenerative Medicine at the University of Edinburgh took cells called fibroblasts from a mouse embryo and turned them into a completely different type of cell called thymus cells, using a technique called reprogramming.

The reprogrammed cells changed shape to look like thymus cells and were also capable of supporting development of T cells in the lab – a specialised function that only thymus cells can perform.


When the researchers mixed reprogrammed cells with other key thymus cell types and transplanted them into a mouse, the cells formed a replacement thymus. The new organ had the same structure, complexity and function as a healthy adult thymus.

It is the first time that scientists have made an entire living organ from cells that were created outside of the body by reprogramming.


Doctors have already shown that patients with thymus disorders can be treated with infusions of extra immune cells or transplantation of a thymus organ soon after birth. The problem is that both are limited by a lack of donors and problems matching tissue to the recipient.

With further refinement, the researchers hope that their lab-grown cells could form the basis of a thymus transplant treatment for people with a weakened immune system.

The technique may also offer a way of making patient-matched T cells in the laboratory that could be used in cell therapies.

Such treatments could benefit bone marrow transplant patients, by helping speed up the rate at which they rebuild their immune system after transplant.


The discovery offers hope to babies born with genetic conditions that prevent the thymus from developing properly. Older people could also be helped as the thymus is the first organ to deteriorate with age.


The study is published today in the journal Nature Cell Biology.

Professor Clare Blackburn from the MRC Centre for Regenerative Medicine at the University of Edinburgh, who led the research, said: "Our research represents an important step towards the goal of generating a clinically useful artificial thymus in the lab."


"This is an exciting study but much more work will be needed before this process can be reproduced in a safe and tightly controlled way suitable for use in humans."

Dr Rob Buckle, Head of Regenerative Medicine at the MRC


Abstract
A central goal of regenerative medicine is to generate transplantable organs from cells derived or expanded in vitro. Although numerous studies have demonstrated the production of defined cell types in vitro1, the creation of a fully intact organ has not been reported. The transcription factor ?forkhead box N1 (?FOXN1) is critically required for development of thymic epithelial cells2, 3 (TECs), a key cell type of the thymic stroma4. Here, we show that enforced ?Foxn1 expression is sufficient to reprogramme fibroblasts into functional TECs, an unrelated cell type across a germ-layer boundary. These ?FOXN1-induced TECs (iTECs) supported efficient development of both ?CD4+ and CD8+ T cells in vitro. On transplantation, iTECs established a complete, fully organized and functional thymus, that contained all of the TEC subtypes required to support T-cell differentiation and populated the recipient immune system with T cells. iTECs thus demonstrate that cellular reprogramming approaches can be used to generate an entire organ, and open the possibility of widespread use of thymus transplantation to boost immune function in patients.


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