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N-acetyl Cysteine Protects Pulp Cells from Resin Toxins in vivo
A. Paranjpe ,
E.C. Sung,
N.A. Cacalano,
W.R. Hume and
A. Jewett*
The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, The Jonsson Comprehensive Cancer Center (JCCC), Dental Research Institute, Division of Oral Biology and Medicine, UCLA Schools of Dentistry and Medicine, University of California, 10833 Le Conte Ave., Los Angeles, CA 90095, USA
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Figure 1. NAC protects the pulp cells from undergoing cell death and growth inhibition after composite restorations in vivo. (A) Nine 8-week-old male rats were divided into 3 groups where (A) no restoration, (B) composite restoration, or (C) composite restoration with NAC was applied. Five hrs after restoration, the teeth were split open, the pulp tissue was removed, and the pulp cells were prepared as described in MATERIALS & METHODS. Dental pulp stromal cells from each group were cultured in media with a combination of β-glycerophosphate (10 mM) and ascorbic acid (50 µg/mL) for 4 wks, after which photographs were taken by means of an inverted microscope (mag. 20X). The results are representative of 3 independent experiments. (B) Rat dental pulp stromal cells were prepared as indicated in Fig. 1A. Five wks after the culture of dental pulp stromal cells, they were trypsinized, and the cell numbers were determined for each group. The results are representative of 3 independent experiments. The cells were counted in triplicate and presented as mean ± standard deviation. p  0.001 for differences between the composite- and ‘composite with NAC’-treated groups. (C) Rat dental pulp stromal cells were prepared as indicated in Fig. 1A. After 5 wks of culture, dental pulp stromal cells were stained, and the levels of alkaline phosphatase staining were determined for each group. The results are representative of 3 independent experiments. Panel C of this Fig. appears in color in the online version.
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Figure 2. NAC protects human dental pulp stromal cells from undergoing cell death and growth inhibition after ex vivo composite restorations. (A) Three freshly extracted human 3rd molars from the same individual were divided into 3 groups where (A) no restoration, (B) composite restoration, or (C) composite restoration with NAC was applied. Restorations were carried out as described in MATERIALS & METHODS. After 5 hrs of restoration, the teeth were fractured, and the pulp tissues were extracted and treated with trypsin-EDTA and collagenase to obtain single-cell suspensions, after which they were cultured in media with β-glycerophosphate (10 mM) and ascorbic acid (50 µg/mL). After 4 wks of culture, photographs were taken via an inverted microscope (mag. 20X). (B) Human dental pulp stromal cells were prepared as described in Fig. 2A. After 6 wks of culture, dental pulp stromal cells were trypsinized, and the cell numbers were determined in each group. The cells were counted in triplicate and presented as mean ± standard deviation. p 0.001 for differences between the composite- and ‘composite with NAC’-treated groups. (C) Human dental pulp stromal cells were prepared as described in Fig. 2A. After 6 wks of culture, supernatants were removed from the cultures, and the levels of VEGF secretion in dental pulp stromal cells (5 x 105/mL) were assessed by a sensitive and specific ELISA for VEGF. p 0.001 for differences between the composite- and ‘composite with NAC’-treated groups.
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Figure 3. NAC protects the human pulp from repeated insults by restorative materials. (A) Human pulp cells extracted from control teeth and those restored with composite in the presence and absence of NAC, as described in Fig. 2A , were grown, and the viable cells from each group (1 x 105) were treated with and without HEMA (0.0082 M) for 18–24 hrs, and the levels of cell death were determined by Annexin V and Propidium Iodide (PI) staining. The numbers in each histogram are the percentages of cells positive for that quadrant. (B) We obtained levels of cell death in each histogram from Fig. 3A by adding the percentages of cells positive in quadrants 1, 2, and 4.
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Journal of Dental Research, Vol. 87, No. 6,
537-541 (2008)
DOI: 10.1177/154405910808700603
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