Each subject will receive one intra-articular injection of autologous mesenchymal stromal cells derived from infrapatellar fat pad (FP-MSC) tissue samples collected from the subject during anterior cruciate ligament (ACL) reconstruction surgery.

Autologous mesenchymal stromal/stem cells extracted from the subject during a routine standard of care ACL reconstruction surgery and reintroduced in one clinic visit approximately 21 days after completion of the surgery. After being removed from the patient, the cells will be cultured, modified, and harvested to become the final investigational product. Each subject will receive 1.5 ml of the investigative drug. This will contain 5x10^7 (50 million) autologous MSCs.

Participants will be asked via a follow-up phone call following injection whether or not they have experienced any adverse events following the injection. They will be assessed at all remaining standard of care follow up visits and staff will inquire about adverse events.

Knee function will be assessed through patient reported responses on the Knee Injury and Osteoarthritis Outcome Score (KOOS) survey via REDCap. The Questionnaire has five subscales which are separately scored (pain, function in daily living, function in sport and recreation, other symptoms and knee-related quality of life). Final score will be determined on a scale of 0-100 where 100 indicates no symptoms and 0 indicates extreme symptoms.

Function will be assessed with the International Knee Documentation Committee Subjective Knee Form (IKDC) which contains sections on knee symptoms, function, and sports activities. Total score will range from 0 (lowest level of function or highest level of symptoms) to 100 points (highest level of function and lowest level of symptoms).

Active and passive Range of Motion (ROM) of the operated and contralateral knee will be documented by the physician. This will be determined by the measurement of angles in each plane at the body's joints.

Pain levels will be assessed using patient reported outcomes via REDCap. The Visual Analogue Scale will ask participants to mark on a line, using a ruler, how much pain they are in. The score is determined by measuring the distance (mm) on the 10-cm line between the "no pain" anchor and the patient's mark, providing a range of scores from 0-100. A higher score indicates greater pain intensity.