Rapid Isolation of Human Stem Cells (Connective Progenitor Cells) From the Distal Femur During Arthroscopic Knee Surgery

Purpose: (1) To safely obtain bone marrow aspirates from the distal femur during arthroscopic knee surgery, (2) to purify and efficiently concentrate connective tissue progenitor cells (CTPs) in the operating room (OR), and (3) to confirm that these are CTPs through their ability to differentiate into bone cells. Methods: Bone marrow aspirates were harvested from the distal femur during arthroscopic knee surgery in 26 patients. Twenty-five matched control subjects were selected to evaluate for increased incidence of complications. CTPs were isolated using a rapid method designed for use in the OR compared with 2 accepted methods. Cytochemical and molecular analysis was used to assess osteogenic potential. Results: Osteogenic potential of the CTPs was confirmed by reverse transcription polymerase chain reaction analysis and cellular staining. Bone marrow was successfully aspirated in 25 cases, with 3 incidences of stiffness in the aspirate group compared with 2 in the control group, 1 incidence of a wound irregularity in the aspirate group compared with 1 in the control group, and 3 incidences of hemarthrosis/persistent effusion in the aspirate group compared with 1 in the control group. The rate of complications for the aspirate group was 36% compared with 25% in the control group. Conclusions: Our intention was to develop a technique for extracting and purifying bone marrow so that the orthopaedic surgeon would have a simple, safe, and efficient process by which to isolate CTPs during arthroscopic knee surgery. This method of aspiration did not lead to a significant increase in complications. Further bone marrow aspirate was successfully purified in the OR, with only a slight increase in surgery time, and resulted in a fractionated layer rich with CTPs. These cells showed osteogenic potential, as evidenced by their osteoblastic differentiation. These CTPs may have future use in enhancing the incorporation of the graft into the bone. Level of Evidence: Level III, matched case-control study.