Tissue Engineering and Stem Cells

Evolved in the late 1980’s, tissue engineering has now promised to improve, repair and replace damaged cells.The field of tissue engineering is rapidly growing with advancement in technology and becoming a major part of the biotech and medical industry. This type of engineering mainly links cellular and molecular biology together with mechanical and chemical engineering.

The National Institute of Biomedical Imaging and Bioengineering describes tissue engineering as a field evolved from biomaterials and the practice of combining scaffolds, cells, and biologically active molecules into functional groups. The ultimate goal is to restore, repair, improve or replace damaged tissues or even the whole organ in some cases. Approved by the Food and Drug Administration, Artificial skin and cartilage are some examples of human engineered tissues.

Regenerative medicine is a field which not only incorporates tissue engineering but also includes research on self healing; the body uses its own systems sometimes with foreign biological material to recreate cells and rebuild tissues and organs.Though this field continues to evolve, we have not yet reached a stage to have a full cure for an injury in the central nervous system of our body. Cells are called the building blocks of tissue, and tissues are the basic unit of function in the body. Cells secrete their own support structures called the extracellular matrix. Not only does this matrix, also called as scaffold support the cell, it also acts as a relay station that helps in signaling various message molecules. Each signal can start a chain of response that determines what would happen. Scientists understand how individual cells respond to signals, interact with the environment and organise into tissues and organs.

Ongoing research focuses on manipulation of these processes to mend damaged tissues and even create new artificial ones (National institute of Biomedical Imaging and Bioengineering).Most treatments for damaged brain or spinal cord cells aim to relieve symptoms and limit further damage. Recent studies into regeneration mechanisms of central nervous system including the discovery of stem cells in the adult brain that can regenerate has given the medical industry a hope and widen their horizon that researchers and scientists can find ways to actually repair Central Nervous System Damage.

Neuroscientists in the mid 1990s learned that some parts of the human brain actually generate new neurons, at least under certain circumstances (NIH- National Institute of Health). The new neurons arise from “neural stem cells” in the fetal and also in adult brain.These undifferentiated cells resemble cells in the developing fetus that give rise to the brain and spinal cord(NIH). The research found that these stem cells could generate most of all the types of cells found in the brain, including the message carriers-neurons.

According to a recent research at Johns Hopkins University, cells derived from embryonic stem cells can restore movement and sensory perception in an animal subjected to amyotrophic lateral sclerosis (ALS). This disease destroys special cells found in the spinal cord, known as motor neurons as they control the movement in the body. Patients with amyotrophic lateral sclerosis experience severe muscle weakness over months which ultimately leads to paralysis and death.

The researchers used a rat model of ALS(Amyotrophic Lateral Sclerosis) to test for possible nerve cell restoring properties of stem cells. The rats were exposed to Sindbis virus, which infects the central nervous system and destroys the motor neurons in the spinal cord. The scientists then assessed the degree of impairment by measuring the rats’ movement using a microscope and quantifying electrical activity in the nerves serving the back limbs. The investigators conducted the experiments with embryonic germ cells that Dr. John Gearhart(Professor and Director of Pediatric Urology at Johns Hopkins) and colleagues isolated from human fetal tissues.

The research had an idea that the embroidered body cells in the non specialised state might become specialised as replacement neurons if they are placed into the area of damaged spinal cord. They carefully injected the prepared cells into the fluid surrounding the spinal cords of paralyzed rats.The response was impressive. Three months later many treated rats were able to move their hind limbs and walk, though clumsily. The research also suggested that the injected cells now continued to develop. They displayed characteristics of mature motor neurons(Kerr, D.A.,, J. (2001). Human embryonic germ cell derivatives facilitate motor recovery of rats with diffuse motor neuron injury).

In another study Professor Shulamit Levenberg, Dean of the Biomedical Engineering Faculty at the Technion, said: "In this project we managed to induce spinal cord regeneration following complete injury to the spinal cord, and this was to the extent where the animal that was totally paralysed started to walk again and also regained sensory perception."

Another study by Israeli scientists at Haifa’s Technion-Israel Institute of Technology used human stem cells in paraplegic rats and the results gave potential hope to humans. The rats regained walking ability and sensory perception.The implanted engineered tissue was fixed on a three dimensional scaffold into the severed spinal cords of test subjects. The human stem cells were induced to support neural growth (staff, TOI, and Stuart Winer , The Times of Israel).