Belletti, Silvana

Gatti, Rita

Govoni, Paolo

Guizzardi, Stefano

Landi, Elena

Scandroglio, Renato

Uggeri, Jacopo

Firenze University Press: E-Journals

IJAE Vol. 115, n. 1/2 (Supplement), 2010
172
In vitro effects of Mg/Sr–substituted hydroxyapatite on 
osteoblast activity
Jacopo Uggeri1, Elena Landi2, Silvana Belletti1, Paolo Govoni1, Renato Scandroglio1, Rita Gatti1, Ste-
fano Guizzardi1
1 Department of Experimental Medicine, Unit of Histology, University of Parma, Italy
2 ISTEC-CNR Institute of Science and Technology for Ceramics, Faenza (RA), Italy
Stoichiometric hydroxyapatite (HA: Ca10(PO4)6(OH)2) has been used as a model for 
the apatite of human bone tissue for many years. Besides calcium, phosphate and car-
bonate, mineral bone contains many inorganic compounds such as sodium, fluoride, 
chloride, magnesium, strontium, zinc, copper and iron. 
This work investigates in vitro effects of magnesium and strontium substitutions in 
the apatite lattice on the behaviour of human osteoblasts. We compared powders of Mg 
and Sr substituted apatites (MgSrHA) with those of stoichiometric HA. Powders were 
prepared as-synthesized and not sintered, which is the most critical condition in terms 
of reactivity towards cells. 
Human osteoblasts were seeded in 24 well plates at the density of 15,000 cells/cm2 in 
DMEM supplemented with 250 µM ascorbic acid and 10% FCS. Treatments with pow-
ders were applied 24 hours after seeding. Dose-response (range 0.1-10 mg/ml) curves 
of HA and MgSrHA powders were performed with MTT assay after 3 days of treatment. 
At 10 mg/ml, viability level of HA-treated osteoblasts was lower than that of MgSrHA-
treated cells (respectively 35% and 50% of untreated cells). At 3 mg/ml viability values 
were comparable and proliferation was slightly hindered (80% of untreated). No sign of 
cell death, evaluated with calcein-propidium iodide assay on living cells, was detectable 
at any of the tested doses. MgSrHA and HA did not affect cell proliferation (evaluated 
by cell counting and cell protein content) after 3 or 7 days of treatment with 0.3 and 1 
mg/ml. At these dosages, alkaline phosphatase (ALP) activity was not affected after 
3 days, but was slightly lower than that of untreated cells at 0.3 mg/ml after 7 days. 
Calcium deposition was measured with red alizarin after 7, 14 and 21 days of treatment 
with 0.3 or 1 mg/ml of powders in the presence of 100 nM dexamethasone and 10 mM 
β-glicero phosphate. Calcium deposition increased in a time-dependent way and was 
highly stimulated in cells treated with both powders.
These preliminary results suggest that MgSrHA has no toxicity effects and seems to 
have a better biocompatibility than stoichiometric HA. Further investigations are need-
ed to elucidate the cell-biomaterial interactions.
Key words
Bone regeneration, synthetic apatite, biomaterial, osteoblast


In vitro effects of Mg/Sr–substituted hydroxyapatite on osteoblast activity

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In vitro effects of Mg/Sr–substituted hydroxyapatite on osteoblast activity

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