van Lent PLEM, Holthuysen AEM, van Rooijen N, van de Putte LBA, van den Berg WB.  Local removal of phagocytic synovial lining cells by clodronate-liposomes decreases cartilage destruction during collagen type II arthritis. Ann Rheum Dis. 1998 Jul 1;57(7):408–13.


OBJECTIVE: To investigate whether local removal of phagocytic synovial lining cells (SLCs) from the knee joint before onset of collagen type II arthritis has an effect on development of cartilage destruction.

METHODS: Phagocytic SLCs were selectively depleted by a single injection of clodronate laden liposomes in the knee joint seven days before induction of collagen type II arthritis (CIA). Clodronate laden liposomes were given in one knee joint either alone or in combination with a short-term oral treatment of dexamethasone. Cartilage damage including proteoglycan depletion and chondrocyte death was measured in total knee joints sections stained with safranin-o or haematoxylin.

RESULTS: Local removal of phagocytic SLCs, seven days before arthritis onset, prevented cell influx for the larger part. Chondrocyte death was significantly decreased in the SLC depleted arthritic joint both at an early (6 days) and late (12 days) time point after CIA induction. However, depletion of proteoglycans from femoral and patellar cartilage layers was not prevented. If the mild acute inflammation caused by a single clodronate laden liposome injection in the left knee joint, was blocked by a short-term (on consecutive days 9, 8, 7, 6, 5 before CIA onset) oral treatment with dexamethasone, cell influx, but also proteoglycan depletion was almost completely blocked. In the contralateral control right knee joint prominent cell influx and severe cartilage damage was observed, indicating that there was no effect of dexamethasone anymore at the onset of CIA.

CONCLUSIONS: This study shows that removal of phagocytic lining cells before CIA induction, particularly in the presence of a short-term treatment with dexamethasone, decreases cartilage destruction.

Clodronate Concentration Total Lipid Concentration Lipid Composition Lipid Mole % Liposome Type Control Liposomes Control Free Clodronate
5 mg/ml 23.5 mg/ml EPC/chol 84/16 MLV PBS ND
Animal Description Clodronate Dose Dosing Method/Site Target Phagocytes Systemic Dosing? Systemic Results
DBA/1 lac J, male, 10-12 w 30 µg/6 µl intra-articular/knee eosin/hematoxylin stained no N/A


    1. Liposome prep method cited—
      van Rooijen N, Sanders A. Liposome mediated depletion of macrophages: mechanism of action, preparation of liposomes and applications. Journal of Immunological Methods. 1994 Sep 14;174(1–2):83–93.
    2. Mice were given intra-articular injections of clodronate liposomes in one knee while PBS or PBS liposomes were injected into the contralateral knee.

Experimental treatment timeline from van Lent, et. al., 1996. Arthritis onset is set at day 28 when the LPS is dosed. Macroscopic paw edema is visible from day 30.

  1. Mice were sacrficed at 6 d or 12 d post-onset of arthritis and joints stanined with eosin/hematoxylin (cells) or safrinin-o (proteoglycan).


  1. Cartilage damage measured by proteoglycan (PG) depletion was similar in all animals despite effective synovial lining cell (SLC) depletion.
  2. Chrondrocytes are constituent cells of the cartilage that synthesize and degrade cartilage components.
  3. At 6 d post-onset, chondrocyte death in the femur was reduced by 25% in the femur and 90% in the patella and at 12 d, chondrocyte death was reduced by ~75% in the femur and about 50% in the patella.
  4. When dexamethasone treatment is combined with clodronate liposome treatment, PG depletion is also inhibited by 75-80%.