Are regenerative therapies now available to treat patients?

Regenerative therapies are being developed worldwide for virtually every disease or medical condition. Several of them have advanced to clinical studies, which means they are being tested on human subjects. There are, however, few regenerative therapies that have been approved for widespread use. 

One well established therapy is the use of stem cells in bone marrow transplantation. Hematopoietic stem cells (HSCs), present in bone marrow and precursors to all blood cells, are currently the only type of stem cells commonly used for therapy. Doctors have been transferring HSCs in bone marrow transplants since the 1960s. Advanced techniques for collecting or "harvesting" HSCs are now used to treat leukemia, lymphoma and several inherited blood disorders.

More recently, living skin equivalents have been approved for treatment of diabetic foot ulcers, venous leg ulcers, and pressure ulcers. Not surprisingly, the more complex the tissue or organ system, the longer it will take to bring products safely to market.

One example of a complex issue facing regenerative medicine scientists is the growth of blood vessels in tissues and organs. Vascular tissues are responsible for transporting nutrients and waste through tissue, and without their proper function replacement tissues will not survive. 

Among the other challenges facing scientists are:

• Fully understanding the processes of how cells, tissues and organ systems interact and communicate with each other
• Improving control of tissue development
• Integrating laboratory grown tissues into actual living bodies
• Fully understanding and controlling the immune response so that replacement tissues are not rejected by the body
• Developing techniques to mass-produce engineered cells and tissues
• Developing handling and storage procedures for regenerated tissues to effectively manage and preserve tissue supplies and ensure consistent safety and quality

As scientists successfully address these challenges, the field will progress and more treatments will become widely available.

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Who will benefit from regenerative therapies?

Millions of people worldwide can benefit from regenerative therapies. In the U.S. alone, the annual need for organ replacement therapies increases by about 10 percent each year¹, and the number of patients on transplant waiting lists who die is staggeringly high. In the year 2000, more than 1,700 people died while waiting for a liver transplant; nearly 3,000 died while waiting for a kidney transplant; 600 while waiting for a heart transplant; and 500 while waiting for a lung transplant.² 

Chronic disease exacts a staggering toll. In the U.S. alone...

• Some 26,000 people die each year from chronic liver disease. (Hepatitis C-associated chronic liver disease is the most frequent indication for liver transplantation among adults.) 
• More than 68,000 deaths are recorded annually from diabetes mellitus, while end-stage renal disease — resulting from diabetes or hypertension — affects more than a quarter million Americans. (It is estimated that more than 10 million diagnosed, and 5 million undiagnosed Americans suffer from diabetes.) 
• More than 60 million people have cardiovascular disease, and more than 1 million heart attacks occur each year with nearly 50 percent resulting in death. 
• 15 million Americans have chronic obstructive pulmonary disease, which claims an additional 110,000 lives each year. 
• Tens of thousands suffer from ocular conditions ranging from retinitis pigmentosa to macular degeneration.³  
  

Almost half the national health care bill — more than $400 billion — is spent each year on patients suffering from organ failure or tissue loss. An estimated 8 million surgeries are performed annually to treat these conditions, yet some 4,000 people die while waiting for an organ transplant and an additional 100,000 die without even qualifying for the waiting list. 

Regenerative medicine products are already changing the practice of medicine. Bioengineered skin products were the first to be used, for the treatment of chronic wounds and burns, and tissue-engineered cartilage is helping to repair damaged joints. Other experimental regenerative techniques are being developed to repair bone, heart defects, bladder/pelvic floor problems, and virtually every other medical condition that can be improved through replacement tissues.

Looking to the future, regenerative medicine may well result in nerve regeneration for treatment of such diseases as Parkinson or Alzheimer’s, islet cells for diabetes, and replacement of damaged heart tissue. As biology, engineering and immunology expertise grows, the field may succeed in building three-dimensional organs like bladders, livers, hearts, and kidneys.

¹Malchesky, Paul S. “Artificial Organs and Vanishing Boundaries,” Artificial Organs 25 (2), 75-88 (Feb. 2001).
²United Network for Organ Sharing; Reported number of deaths on the waiting list:  1988-2000.
³Statistics from National Vital Statistics Report, Vol. 49, No 8; National Center for Infectious Disease; and National Center for Health Statistics.