Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

AX5-131
Table AX5-8.3 (cont’d). Bone Cell Cultures Utilized to Test Effects of Lead
Compound
Dose/Concentration
Duration Exposure
Route Species Effects Blood Level Reference
Pb nitrate
0–150 µM
Up to 72 hr
In medium
Pb acetate
0–25 µM
48 hr
In medium
Pb glutamate
4.5 H 10 −5 to
4.5 H 10 −7 M
2, 4, or 6 days
In medium
Pb glutamate
4.5 H 10 −5 M–10 −7 M
1,3, or 5 days
incubation
In medium
Mice (bone
cell isolation
from parietal
bones)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Human
Dental Pulp
Cells
Pb 2+ concentrations of 50 µM and above stimulated release of hydroxyproline and
previously incorporated 45 Ca from organ culture. This did not occur in bone
inactivated by freezing and thawing. Eel calcitonin, bafilomycin A1, and scopadulcic
acid B significantly inhibited Pb mediated 45 Ca release. There was a high correlation
between 45 Ca and PGE 2 release (p < 0.001), inferring Pb-induced bone resorption
mediated by PGE 2. This was further supported by the significant depression of Pbstimulated
45 Ca release that occurred with concurrent exposure to 10 µM of either
indomethacin or flurbiprofen, both inhibitors of cyclooxygenase.
Osteocalcin production in cells treated with 100 pg 1,25-dihydroxyvitamin D 3/mL of
medium and 0 µM Pb 2+ for 16, 24, or 36 h was 20.1 ± 2.1, 23.5 ± 3.4, 26.1 ± 2.5 in cell
digests, and 87.2 ± 3.3, 91.6 ± 6.7, 95.1 ± 5.2 in the medium, respectively. The
presence of 25 µM Pb 2+ in the medium, reduced osteocalcin levels to as low as 30% of
control levels.
Cells treated with 0, 5, 10, or 25 µM Pb acetate for 24 h, followed by an additional
24 h exposure to 0 or 100 pg of 1,25-dihydroxyvitamin D3 and continued Pb 2+
exposure, resulted in a concentration-dependent reduction of 1,25-dihydroxyvitamin
D3-stimulated osteocalcin secretion. 10 µM Pb resulted in medium osteocalcin levels
similar to control levels, however, 25 µM Pb resulted in about a 30% decrease.
Cellular osteocalcin levels were unaffected.
In the presence of serum in the cultures, concentrations of Pb 2+ less than 4.5 H 10 −5 M
had no effect on cell proliferation. In the absence of serum, 4.5 H 10 −7 M Pb 2+
increased proliferation at Day 4 and 4.5 H 10 −6 M Pb 2+ inhibited proliferation at Day 6.
Pb exposure for 48 h (4.5 H 10 −6 M) significantly (p < 0.01) increased total protein
production in cells and media of cultures labeled with [ 3 H] proline, but did not
increase collagen production. Protein synthesis and osteonectin were enhanced in
cells following Pb 2+ exposure.
All concentrations significantly increased cell proliferation on Day 1, 3, and 5 of
exposure in serum free conditions. Pb exposure resulted in dose-dependent decrease
in intracellular protein and procollagen I production over 5 days. In presence of serum
only, 4.5 H 10 −5 M Pb 2+ significantly increased protein production, however, at that
same concentration Pb significantly decreased osteocalcin production (i.e., reduced the
level of osteocalcin by 55% at 12 hr).
Not applicable Miyahara et al.
(1995)
Not applicable Long et al. (1990)
Not applicable Sauk et al. (1992)
Not applicable Thaweboon et al.
(2002)