The common pathway for almost all injuries and diseases is inflammation. Can it be controlled? And if so, should it?

Inflammation Friend or Foe

Inflammation is what happens when tissues are injured. The tissue damage breaks blood vessels and collagen fibers. Blood and fluid from the extracellular space are released into the area of damage, and swelling occurs. The cells that live in those tissues and in the blood then release bioactive factors. These factors call on the body’s repair systems, including stem cells, to initiate repair. This sequence— from removing dead tissue to producing new repair tissue—is defined as healing.  

Tissues such as bone and (possibly) brain tissue can be restored to normal. Other tissues form scar first before a degree of remodeling toward normal occurs. This process can be accelerated or delayed. Patients who walk around on their repaired knees too much and too early, for instance, have longer recovery times, due in part to increased swelling.  

Much of our research, and that of many other clinics, focuses on accelerating tissue repair by first reducing the swelling associated with inflammation. Ice, elevation, and soft tissue massage have been employed for centuries for this purpose. Today we are utilizing and investigating injections of growth factors: potent anti-inflammatories that recruit additional stem-cell-derived self-repair cells called progenitors to the site of injury. Their ability to shrink swollen joints and tissues is sometimes dramatic.

Inflammation can also happen due to chemical or biologic stimuli. Here is an example: When the body recognizes some types of cancer cells, the inflammatory response cells of the immune system release free radicals or free oxygen molecules that destroy the abnormal cells. This response probably occurs thousands (or even millions) of times each day, as abnormal cells are continually created and the body eliminates them before they become a problem. This is where we begin to wonder if we really should take anti-inflammatory medications, load up on free radical suppressing vitamins, and/or use antioxidant skin creams. Reducing the protective response that keeps us alive may risk defanging our natural defenses.

Inflammation is believed to be a primary cause of cardiovascular disease. Diets rich in meat and animal fats have been shown to promote vessel wall disease in the arteries that carry blood to our heart muscles. This inflammation not only damages the muscular wall of the artery; it opens up cracks that permit plaque or clots to form on the vessel walls. These clots narrow the arteries—lowering blood flow and raising blood pressure. And they sometimes break off, leading to heart attacks and strokes. In this case, it appears that lowering inflammation must be good—but the best tools for this are primarily diet and exercise. Clearly, the growth factors and stem cell attractants we use for sports-related soft tissue injuries could play a significant role in addressing cardiovascular disease, once we discover how to work with them within these hard-to-access organs.

Inflammation is also believed to be a primary instigator of Alzheimer’s and other forms of dementia. Here the linkages are less clear and the mode of action more complex. But just as in cardiovascular disease, reducing plaque deposition in blood vessels may play an important role.

So, inflammation can be both a friend and a foe. Like the proverbial fish (or guest), it is welcome for a few days, but stinks if it sticks around too long.

Medically authored by
Kevin R. Stone, MD
Orthopaedic surgeon, clinician, scientist, inventor, and founder of multiple companies. Dr. Stone was trained at Harvard University in internal medicine and orthopaedic surgery and at Stanford University in general surgery.