Stem cells are present in most adult tissues. Harvesting is most commonly from adipose tissue or bone marrow. Both have advantages and disadvantages. For adipose tissue, there is typically more than adequate amounts for harvest and the number of stems cells per unit volume is greater than bone marrow.
There are several types of adipose tissue processing techniques. The technique used at the OrthoIndy Stem Cell, Ortho-Biologics and Regenerative Medicine program is a proprietary technique (LipoGems®) that involves minimal manipulation and gentle handling of the fat tissue that is harvested by “lipoaspiration” not formal liposuction.
This process is enzyme-free does not involve centrifugation of the tissue. Through mechanical emulsification (thorough mixing) of the tissue, the size of the fat clusters is reduced. Sterile saline is employed during processing to wash and rinse the tissue, which reduces inflammatory impurities, such as oil residues and blood. During the process, the tissues are exposed to only mild mechanical forces, which maintain the native microenvironment of adipose tissue. This microenvironment includes the microvasculature surrounding the adipocytes. The microvasculature has small adherent cells (the pericytes). A subset of these specialized cells is adult mesenchymal stem cells. These small adipose microspheres with their microenvironment can be injected through a 22-gauge needle.
Once injected, the stem cells are signaled to leave the microvasculature and migrate to areas of inflammation and/or injury. They are like “traveling” chemical factories as they excrete a variety of beneficial bioactive molecules.
The knee naturally has its own fat pad. The injected adipose microspheres can aid in one hypothesized function of the natural fat pad: a source of stem cells for the knee.