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Adaptive beta-cell proliferation is severely restricted with advanced age.

Rankin MM, Kushner JA - Diabetes (2009)

Bottom Line: However, it is unknown whether this adaptive beta-cell regeneration capacity is retained into old age.We assessed adaptive beta-cell proliferation capacity in adult mice across a wide range of ages with a variety of stimuli: partial pancreatectomy, low-dose administration of the beta-cell toxin streptozotocin, and exendin-4, a glucagon-like peptide 1 (GLP-1) agonist. beta-Cell proliferation was measured by administration of 5-bromo-2'-deoxyuridine (BrdU) in the drinking water.Basal beta-cell proliferation was severely decreased with advanced age.

View Article: PubMed Central - PubMed

Affiliation: Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.

ABSTRACT

Objective: Regeneration of the insulin-secreting beta-cells is a fundamental research goal that could benefit patients with either type 1 or type 2 diabetes. beta-Cell proliferation can be acutely stimulated by a variety of stimuli in young rodents. However, it is unknown whether this adaptive beta-cell regeneration capacity is retained into old age.

Research design and methods: We assessed adaptive beta-cell proliferation capacity in adult mice across a wide range of ages with a variety of stimuli: partial pancreatectomy, low-dose administration of the beta-cell toxin streptozotocin, and exendin-4, a glucagon-like peptide 1 (GLP-1) agonist. beta-Cell proliferation was measured by administration of 5-bromo-2'-deoxyuridine (BrdU) in the drinking water.

Results: Basal beta-cell proliferation was severely decreased with advanced age. Partial pancreatectomy greatly stimulated beta-cell proliferation in young mice but failed to increase beta-cell replication in old mice. Streptozotocin stimulated beta-cell replication in young mice but had little effect in old mice. Moreover, administration of GLP-1 agonist exendin-4 stimulated beta-cell proliferation in young but not in old mice. Surprisingly, adaptive beta-cell proliferation capacity was minimal after 12 months of age, which is early middle age for the adult mouse life span.

Conclusions: Adaptive beta-cell proliferation is severely restricted with advanced age in mice, whether stimulated by partial pancreatectomy, low-dose streptozotocin, or exendin-4. Thus, beta-cells in middle-aged mice appear to be largely postmitotic. Young rodents may not faithfully model the regenerative capacity of beta-cells in mature adult mice.

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Low-dose-BrdU is not toxic to proliferating β-cells. BrdU was continuously administered in the drinking water for 2 weeks to a cohort of mice aged 1 month that were then compared with untreated control mice. A: Representative pancreatic β-cell histology of pancreas sections immunostained with antibodies against insulin (yellow), Ki67 (red), and BrdU (green) and counterstained with DAPI (blue) and photographed with a 40× objective. White arrows indicate insulin and BrdU copositive cells; red arrows denote insulin and Ki67 copositive cells. Scale bars: 100 μm in full image and 20 μm within inset. B: Quantitative analysis of β-cell proliferation as measured by Ki67 incorporation. Continuous BrdU treatment does not slow β-cell proliferation. Results are expressed as percent Ki67-positive β-cells and represent means ± SEM (n = 5 animals per group). (A high-quality digital representation of this figure is available in the online issue.)
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Figure 5: Low-dose-BrdU is not toxic to proliferating β-cells. BrdU was continuously administered in the drinking water for 2 weeks to a cohort of mice aged 1 month that were then compared with untreated control mice. A: Representative pancreatic β-cell histology of pancreas sections immunostained with antibodies against insulin (yellow), Ki67 (red), and BrdU (green) and counterstained with DAPI (blue) and photographed with a 40× objective. White arrows indicate insulin and BrdU copositive cells; red arrows denote insulin and Ki67 copositive cells. Scale bars: 100 μm in full image and 20 μm within inset. B: Quantitative analysis of β-cell proliferation as measured by Ki67 incorporation. Continuous BrdU treatment does not slow β-cell proliferation. Results are expressed as percent Ki67-positive β-cells and represent means ± SEM (n = 5 animals per group). (A high-quality digital representation of this figure is available in the online issue.)

Mentions: Our results indicate that partial pancreatectomy–induced β-cell regeneration capacity may be severely restricted with advanced age. However, we were concerned about potential BrdU toxicity, which could theoretically reduce β-cell proliferation. Continuous low-dose BrdU administration in the drinking water is generally well tolerated and does not severely reduce β-cell proliferation compared with short-term infusions of high-dose BrdU (17). However, Hellerstein and colleagues (26) recently reported that continuous BrdU administration reduces proliferation of islet components by ∼25%, as measured by heavy water incorporation into DNA. Consequently, we tested for BrdU-associated toxicity by assessing β-cell proliferation in our cohort, as measured by the presence of Ki67. We administered BrdU in the drinking water or control water to a cohort of 1-month-old mice for 2 weeks, after which they were killed. Reassuringly, Ki67-positive β-cells were equivalent in BrdU-treated and untreated pancreata (2.29 ± 0.31 vs. 2.51 ± 0.25%, respectively; P = 0.59) (Fig. 5). Thus, prolonged infusion of BrdU does not influence β-cell proliferation, as measured by Ki67 expression. This result indicates that limited β-cell regeneration in aged mice cannot be readily explained by BrdU toxicity to proliferating β-cells.


Adaptive beta-cell proliferation is severely restricted with advanced age.

Rankin MM, Kushner JA - Diabetes (2009)

Low-dose-BrdU is not toxic to proliferating β-cells. BrdU was continuously administered in the drinking water for 2 weeks to a cohort of mice aged 1 month that were then compared with untreated control mice. A: Representative pancreatic β-cell histology of pancreas sections immunostained with antibodies against insulin (yellow), Ki67 (red), and BrdU (green) and counterstained with DAPI (blue) and photographed with a 40× objective. White arrows indicate insulin and BrdU copositive cells; red arrows denote insulin and Ki67 copositive cells. Scale bars: 100 μm in full image and 20 μm within inset. B: Quantitative analysis of β-cell proliferation as measured by Ki67 incorporation. Continuous BrdU treatment does not slow β-cell proliferation. Results are expressed as percent Ki67-positive β-cells and represent means ± SEM (n = 5 animals per group). (A high-quality digital representation of this figure is available in the online issue.)
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Related In: Results  -  Collection

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Figure 5: Low-dose-BrdU is not toxic to proliferating β-cells. BrdU was continuously administered in the drinking water for 2 weeks to a cohort of mice aged 1 month that were then compared with untreated control mice. A: Representative pancreatic β-cell histology of pancreas sections immunostained with antibodies against insulin (yellow), Ki67 (red), and BrdU (green) and counterstained with DAPI (blue) and photographed with a 40× objective. White arrows indicate insulin and BrdU copositive cells; red arrows denote insulin and Ki67 copositive cells. Scale bars: 100 μm in full image and 20 μm within inset. B: Quantitative analysis of β-cell proliferation as measured by Ki67 incorporation. Continuous BrdU treatment does not slow β-cell proliferation. Results are expressed as percent Ki67-positive β-cells and represent means ± SEM (n = 5 animals per group). (A high-quality digital representation of this figure is available in the online issue.)
Mentions: Our results indicate that partial pancreatectomy–induced β-cell regeneration capacity may be severely restricted with advanced age. However, we were concerned about potential BrdU toxicity, which could theoretically reduce β-cell proliferation. Continuous low-dose BrdU administration in the drinking water is generally well tolerated and does not severely reduce β-cell proliferation compared with short-term infusions of high-dose BrdU (17). However, Hellerstein and colleagues (26) recently reported that continuous BrdU administration reduces proliferation of islet components by ∼25%, as measured by heavy water incorporation into DNA. Consequently, we tested for BrdU-associated toxicity by assessing β-cell proliferation in our cohort, as measured by the presence of Ki67. We administered BrdU in the drinking water or control water to a cohort of 1-month-old mice for 2 weeks, after which they were killed. Reassuringly, Ki67-positive β-cells were equivalent in BrdU-treated and untreated pancreata (2.29 ± 0.31 vs. 2.51 ± 0.25%, respectively; P = 0.59) (Fig. 5). Thus, prolonged infusion of BrdU does not influence β-cell proliferation, as measured by Ki67 expression. This result indicates that limited β-cell regeneration in aged mice cannot be readily explained by BrdU toxicity to proliferating β-cells.

Bottom Line: However, it is unknown whether this adaptive beta-cell regeneration capacity is retained into old age.We assessed adaptive beta-cell proliferation capacity in adult mice across a wide range of ages with a variety of stimuli: partial pancreatectomy, low-dose administration of the beta-cell toxin streptozotocin, and exendin-4, a glucagon-like peptide 1 (GLP-1) agonist. beta-Cell proliferation was measured by administration of 5-bromo-2'-deoxyuridine (BrdU) in the drinking water.Basal beta-cell proliferation was severely decreased with advanced age.

View Article: PubMed Central - PubMed

Affiliation: Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.

ABSTRACT

Objective: Regeneration of the insulin-secreting beta-cells is a fundamental research goal that could benefit patients with either type 1 or type 2 diabetes. beta-Cell proliferation can be acutely stimulated by a variety of stimuli in young rodents. However, it is unknown whether this adaptive beta-cell regeneration capacity is retained into old age.

Research design and methods: We assessed adaptive beta-cell proliferation capacity in adult mice across a wide range of ages with a variety of stimuli: partial pancreatectomy, low-dose administration of the beta-cell toxin streptozotocin, and exendin-4, a glucagon-like peptide 1 (GLP-1) agonist. beta-Cell proliferation was measured by administration of 5-bromo-2'-deoxyuridine (BrdU) in the drinking water.

Results: Basal beta-cell proliferation was severely decreased with advanced age. Partial pancreatectomy greatly stimulated beta-cell proliferation in young mice but failed to increase beta-cell replication in old mice. Streptozotocin stimulated beta-cell replication in young mice but had little effect in old mice. Moreover, administration of GLP-1 agonist exendin-4 stimulated beta-cell proliferation in young but not in old mice. Surprisingly, adaptive beta-cell proliferation capacity was minimal after 12 months of age, which is early middle age for the adult mouse life span.

Conclusions: Adaptive beta-cell proliferation is severely restricted with advanced age in mice, whether stimulated by partial pancreatectomy, low-dose streptozotocin, or exendin-4. Thus, beta-cells in middle-aged mice appear to be largely postmitotic. Young rodents may not faithfully model the regenerative capacity of beta-cells in mature adult mice.

Show MeSH
Related in: MedlinePlus