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June 17, 2010

Stem Cells from Fat Will be used to Heal Bones Faster and Other New Medical Technology

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1. Dr. Kent Leach will use stem cells derived from human adipose tissue (fat) to stimulate the formation of microvascular networks (neovascularization) within developing bone. Bone regeneration depends upon the formation of these networks to deliver oxygen and other nutrients necessary for healing. Most current clinical approaches inject pure stem cells systemically or locally, yet bone formation is hit or miss.

Dr. Leach’s project will embed the stem cells in a special gel to implant them directly in the injured site. This “composite hydrogel” contains a mixture of different polymers that controls the rate at which the gel degrades. Materials that degrade too slowly impede tissue formation, while gels that degrade too quickly will not hold stem cells in place. Scientists mix stem cells and other chemicals into the gel, and inject it, in liquid form, into the bone fracture or defect. The gel congeals, entrapping stem cells at the defect site to promote bone repair. Leach’s team has already developed a composite hydrogel and used it to deliver stem cells derived from bone marrow to injured horses.

This approach has two advantages over current approaches. First, stem cells from the patient’s own body have a better chance of succeeding than donor cells. The process of extracting bone marrow to obtain stem cells is excruciatingly painful, requires several days of recovery time, and is not feasible for severely injured or weakened patients. Doctors can obtain stem cells from fat with minimal invasiveness
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Explosive blasts, rarely encountered in civilian life, cause about 2/3 of the injuries in Iraq. Musculoskeletal injuries account for about 70% of war wounds, and 55% of those are wounds to the arms and legs. Fractures account for 26% of combat injuries.

2. Dental pulp will be used to create induced pluripotent stem cell banks.

Dental pulp cells are an optimal source of iPS cells, since they are easily obtained from extracted teeth and can be expanded under simple culture conditions.

Direct reprogramming of patients' somatic cells would allow for cell transplantation therapy free from immune-mediated rejection. A large pool of stem cells from many people would make it very likely that there would be perfect matching of stem cells for people who did not donate to the bank. Receiving donations from other people still means that there is the issues of immune rejection, but at least there would be very close typing matches.

3. A new implant using laser melting improves the conditions for the bone healing process.
The Laser melting technique is adapting technology used for rapid 3d manufacturing for medical purposes.
Over a period of months or even years, the bone will gradually replace the porous Resobone, until nothing but natural bone is left. Resobone cannot stand up to severe stress, so its use will be limited primarily to facial, maxillary (upper jaw area) and cranial bones. So far, it has been able to close fissures up to 25 square centimeters in size. The patches can be created in anywhere from a few hours to over one night. A stronger version of Resobone needs to be developed for other kinds of bone injuries or some other brace or support must be built to work with Resonbone for bones that are weight bearing.

Unlike the conventional bony substitutes to date, it is not made up as a solid mass, but is porous instead. Precise little channels permeate the implant at intervals of just a few hundred micrometers. Its precision fit and perfect porous structure, combined with the new biomaterial, promise a total bone reconstruction that was hitherto impossible to achieve,as Dr. Ralf Smeets of the University Medical Center of Aachen summarizes the findings of the first tolerability studies.

The porous canals create a lattice structure which the adjacent bones can grow into. Its basic structure consists of the synthetic polylactide, or PLA for short. The stored granules from tricalcium phosphate (TCP) ensure rigidity and stimulate the bone‘s natural healing process. As pastes, granulates and semi-finished products, TCP and PLA already have proven to be degradable implants. The body can catabolize both substances as rapidly as the natural bones can regrow. But the material can only be applied in places where it will not be subject to severe stress: Thus, the »Resobone« implants will primarily replace missing facial, maxillary and cranial bones. Currently, they are able to close fissures of up to 25 square centimeters in size. Their unique structure is made possible through a manufacturing process that was developed at the Fraunhofer Institute for Laser Technology ILT in Aachen for the development of industrial prototypes – Selective Laser Melting (SLM): A razor-thin laser beam melts the pulverized material layer-by-layer to structures that may be as delicate as 80 to 100 micrometers.


4. Livers could be grown in the laboratory for transplantation into humans within five years.

The new technique works by effectively chemically stripping the old liver down too its basic "scaffold" or exoskeleton in a process of called "decellularisation".

Onto this frame of connective tissue and blood vessels, they then regrow the new liver using stem cells from the patient. Stem cells from embryos could also be used. The effectively brand new liver is then transplanted back into the patient.

At the moment the technique will require donor organs but it is hoped that eventually pig's livers or artificial scaffolds can be used instead – effectively avoiding donors altogether.

Dr Martin Yarmush, co-author of the study in Nature Medicine, said the quarter of a million donor livers discarded each year because they are not suitable for transplantation would be an obvious source of supply for the creation of these scaffolds.


5. Burns experts from the University of Sydney and Concord Hospital have started animal trials of a living skin that is grown outside the body and is completely functional when grafted on to the body.

Unlike traditional skin grafts, which involve only the thin outer layer of the skin known as the epidermis, the new skin will be able to replace the crucial second layer of skin called the dermis. This layer is responsible for functions such as temperature control, perspiration, toughness and elasticity, and when it is missing, the body reacts by producing large swathes of scarring underneath the skin graft.

It currently takes the body weeks to grow into a skin graft and in that time a lot of excess elastic fibres and collagen will be produced that will then turn into a scar

Professor Maitz and his team have developed an artificial scaffold into which the patient's own skin cells can be implanted, allowing them to grow into a functioning replacement dermis.


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