Since the procedure uses stem cells derived from your own fat (autologous), the risk of rejection is minimized. However, once the stem cells are introduced into the body, mild immune and regenerative responses may occur. As a result, some patients may occasionally experience symptoms that can feel like side effects, such as mild cold-like symptoms or muscle aches. These symptoms are typically temporary and usually subside within 1-2 days, so there is no need for significant concern.