Figure 3.

The effect of MMPIs on angiogenesis and osteoclast invasion of caudal vertebrae of neonatal mice in vivo. A: Schematical representation of angiogenesis and osteoclastogenesis in the caudal vertebrae in the neonatal mouse tails under control conditions (vehicle). Tails were processed and double-stained for TRAcP (red) and lectin (brown). At day 2 post partem (p.p.) osteoclast-precursors and blood capillaries have started to invade the bone collar at caudal vertebrae 11 and 10 respectively (V11, V10). Four days later, at day 6 p.p., osteoclast-precursors and capillaries have progressed in a distal manner and their invasion fronts can now be identified at caudal vertebrae 16 (capillaries, V16) and 18 (osteoclasts, V18). Representative images of vertebra 3, 14, and 23 are shown. Original magnifications, ×200 (V14, 23) and ×400 (V3). Open arrowheads denote lectin-positive capillaries. oc, osteoclast; bm, bone marrow; ml, calcified cartilage. B: Distal progression of the invasion front of blood capillaries and osteoclast-precursors in neonatal mouse tails after 4 days of treatment (day 6 p.p.) with CH5902 or CH3921. Angiogenesis was significantly inhibited by both MMPIs (V12 and V10 for CH5902 and CH3921, respectively). In contrast to CH5902, CH3921 did not affect osteoclastogenesis in vivo. Representative images of vertebrae 14 (V14) are shown. Original magnification, ×200. Open arrowheads denote lectin-positive capillaries. oc, osteoclast. C: Administration of various doses of marimastat was found to be cytotoxic and lead to severe side effects such as growth retardation and, in most cases, death (see text). Morphological changes of osteoclasts and sinusoids after four days of treatment with 6 mg/kg/day marimastat in caudal vertebra 14 (V14; C). Neither osteoclasts nor blood capillaries have invaded the calcified cartilage and show signs of severe side effects. Original magnifications, ×200 and ×400. Open arrowheads denote lectin-positive capillaries. oc, osteoclast.