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(Stroke. 2000;31:534.)
© 2000 American Heart Association, Inc.

Original Contributions

Toxicity of Dutch (E22Q) and Flemish (A21G) Mutant Amyloid ß Proteins to Human Cerebral Microvessel and Aortic Smooth Muscle Cells

Zhenzhen Wang, MD, PhD; Remco Natté, MD; Judith A. Berliner, PhD; Sjoerd G. van Duinen, MD, PhD Harry V. Vinters, MD

From the Department of Pathology and Laboratory Medicine (Neuropathology) (Z.W., H.V.V.), Department of Pathology and Laboratory Medicine (J.A.B.), and Brain Research Institute, Mental Retardation Research Center and Neuropsychiatric Institute (H.V.V.), University of California at Los Angeles School of Medicine; and Departments of Neurology and Pathology, Leiden University Medical Center (Netherlands) (R.N., S.G. van D.).

	Abstract

Top Abstract Introduction Subjects and Methods Results Discussion References Introduction

 
Background and Purpose—Cerebral amyloid angiopathy (CAA) is characterized by the deposition of amyloid ß protein (Aß) in cortical and leptomeningeal vessels of patients with Alzheimer’s disease and hereditary cerebral hemorrhage with amyloidosis, Dutch type. Smooth muscle cells (SMC) from cerebral microvessels (MV) are of particular interest as a site of Aß-related injury because CAA is much more pronounced in the tunica media of cortical arterioles than meningeal arteries. Patients carrying point mutations at residues 22 (E22Q) and 21 (A21G) of Aß show severe CAA with various degrees of brain parenchymal Aß deposition. The purpose of this study was to investigate the effects of 2 mutant E22Q- and A21G-Aß peptides on MV and aortic SMC.

Methods—SMC were isolated from human cerebral MV and aorta. Cell morphology, viability, and proliferation as parameters of Aß toxicity were investigated after 3 days of peptide treatment by trypan blue exclusion and [³H]thymidine incorporation.

Results—E22Q-Aß induced significant decreased cellular proliferation and viability, as well as obvious degeneration of both MV and aortic SMC. A21G-Aß and wild-type Aß did not cause significant toxicity, as judged by cell morphology, viability, or cell proliferation, on either type of SMC.

Conclusions—E22Q-Aß induced greater toxicity in all parameters than A21G-Aß and wild-type Aß with respect to both MV and aortic SMC. A21G-Aß did not show a significant toxic effect on MV and aortic SMC. This differential effect may be linked to cell type–specific processing and metabolism of mutant forms of Aß. Mutations in amyloid precursor protein may lead to CAA by different pathogenetic mechanisms or share an unknown property that distinguishes them from wild-type Aß.

Key Words: amyloid • cerebral circulation • microcirculation • muscle, smooth • mutation

	Introduction

Top Abstract Introduction Subjects and Methods Results Discussion References Introduction

 
Cerebral amyloid angiopathy (CAA) is characterized by the deposition of fibrillar amyloid in the media and adventitia of cerebral cortical and meningeal blood vessels.^{1 2} Amyloid ß protein (Aß) is the main constituent of vascular amyloid in sporadic/Alzheimer disease–associated CAA, Down syndrome, and hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D).^{3 4 5} The presence of amyloid in the cerebrovascular tunica media is closely associated with degeneration of smooth muscle cells (SMC) in this locus.^{1 6 7 8} HCHWA-D is an autosomal dominant disease caused by a point mutation at codon 693 of the ß amyloid precursor protein (APP). This mutation results in a glutamic acid to glutamine substitution at residue 22 (E22Q) of Aß. HCHWA-D patients consistently develop severe CAA and cerebral hemorrhage but only rarely have significant numbers of senile plaques or neurofibrillary tangles within the brain.^{4 9 10} This makes the clinicopathological phenotype of HCHWA-D unique by comparison with clinicopathological phenotypes associated with other APP mutations.^{11 12 13 14 15} This issue is of particular interest when HCHWA-D patients are compared with patients carrying the Flemish APP692 mutation, immediately adjacent to the HCHWA-D mutation site, resulting in a glycine for alanine substitution at residue 21 of Aß (A21G).¹³ In the case of the Flemish APP692 mutation, patients present with a progressive dementia and cerebral hemorrhage. The phenotypes of these 2 APP mutations share severe amyloid angiopathy in cerebral blood vessels, leading to cerebral hemorrhage, but patients carrying the APP692 mutation show classic senile plaques, neurofibrillary tangles, and abundant brain parenchymal amyloid.^{13 16} The different clinical and pathological phenotypes are hypothesized to result, at least in part, from the different effects of Aß peptide containing E22Q and A21G mutations on cerebral microvessel (MV) SMC.

HCHWA-D-Aß_1–40 has been reported to be more toxic than wild-type (Wt) Aß_1–40 to human meningeal SMC.¹⁷ However, cerebral cortical (parenchymal) MV SMC may be of greater interest as a site and target of Aß-related injury, because CAA is much more pronounced in the tunica media of cortical arterioles than meningeal arteries.^{2 6 10} In HCHWA-D, the cortical arterioles appear to be the first affected by Aß deposition.⁴ Furthermore, cerebrovascular SMC show histochemical heterogeneity among vessels in the pia, cerebral cortex, and white matter.¹⁸ Histochemical heterogeneity of SMC is also seen between small and large vessels.¹⁹ This raises the possibility of unique in vitro characteristics of SMC depending on their vessel of origin.

The purpose of this study was to investigate the effect of E22Q-Aß_1–40, A21G- Aß_1–40, and Wt-Aß_1–40 on MV- and aorta-derived SMC.

	Subjects and Methods

Top Abstract Introduction Subjects and Methods Results Discussion References Introduction

 
Brain tissue was obtained from surgical specimens of various patients. MV SMC were isolated from human brain cortex and cultured as previously described.²⁰ SMC phenotype was confirmed by immunohistochemistry using anti–smooth muscle actin antibody 1A4 (DAKO) and by electron microscopy. Human aortic SMC as a control cell line were isolated from aortic specimens obtained from heart donors in the University of California at Los Angeles heart transplant program.²¹ Cells were cultured on standard Dulbecco’s modified Eagle’s medium supplemented with 10% fetal bovine serum and antibiotics. Lyophilized Aß, including E22Q-Aß, A21G-Aß, and Wt-Aß, was obtained from Dr C.G. Glabe (University of California at Irvine). Mutated and Wt-Aß were all Aß_1–40 and will be referred to as Aß in the text. For each experiment, cells between passages 6 and 8 were trypsinized and plated in equal volumes on 12-well dishes under continuous suspension. After 48 hours, the medium was replaced with serum-free medium supplemented with 0.1% bovine serum albumin. After 5 hours, cells were incubated with freshly solubilized Aß dissolved in serum-free medium at a final concentration of 100 µg/mL. Control cultures received the same volume of medium vehicle without peptide. Cell viability was determined at 3 days after peptide incubation by trypan blue dye exclusion. Cells were harvested by treatment with 0.25% trypsin-EDTA, centrifuged, and stained with 0.2% trypan blue for 10 minutes and counted by a hemocytometer. The percentage of dead cells was quantified from 150 to 200 cells from duplicate wells of 4 independent experiments by 2 observers blinded to the specific treatment. [³H]Thymidine incorporation was also examined after 3 days of peptide treatment. Next 1 µCi of [³H]thymidine was added to each well and incubated for 18 hours. Subsequently, cells were rinsed with PBS, fixed in 10% trichloroacetic acid, solubilized in 1N NaOH, and transferred to a scintillation solution. The incorporation of [³H]thymidine was counted by a Beckman liquid scintillation counter. Counting of disintegrations per minute of the control group was considered 100%; the other groups were calculated and expressed as the percentage of disintegrations per minute relative to that of the control group. Samples for each group were analyzed in triplicate wells and repeated 3 to 4 times in independent experiments. The differences in cell proliferation and viability among control and peptide-treated groups were analyzed, and the effect of each treatment on MV SMC with the effect of the same treatment on the aortic SMC was also compared by ANOVA with Bonferroni post hoc test.

	Results

Top Abstract Introduction Subjects and Methods Results Discussion References Introduction

 
MV SMC appeared to exhibit greater sensitivity to E22Q-Aß than A21G-Aß and Wt-Aß in terms of morphology, cell viability, and cell proliferation. Morphological changes were detected in MV SMC after 3 days of incubation with E22Q-Aß but not with A21G-Aß, with Wt-Aß, or in the absence of Aß (Figure 1). Cells exposed to E22Q-Aß showed degenerative changes in the form of obscured cell contours and dark granules and threads in or on cell bodies. However, these cells remained attached to the plates and maintained their size and shape. E22Q-Aß induced a significant increase in the percentage of dead MV SMC compared with the control group and the A21G- and Wt-Aß groups (P<0.001) (Figure 2); the percentage of dead MV SMC exposed to E22Q-Aß was 4 to 5 times greater than in the control group. The [³H]thymidine incorporation was consistently in line with the morphological change and cell viability measurements observed in cells exposed to E22Q-Aß. MV SMC proliferation was strongly inhibited by E22Q-Aß compared with the control group (16% of cell proliferation in E22Q-Aß–treated cells versus 100% in control cells; P<0.001) (Figure 3A). In contrast, A21G- and Wt-Aß had no significant effect on MV SMC morphology, cell viability, and proliferation compared with the control group.

View larger version (139K): [in this window] [in a new window]   Figure 1. Morphological change of cultured human brain MV-derived SMC exposed to various Aß1–40 peptides (100 µg/mL) for 3 days. A, Control (no peptide). B, Dutch E22Q-Aß. C, Flemish A21G-Aß. D, Wt-Aß. Prominent SMC degeneration is seen only with Dutch E22Q-Aß. Magnification x30.

View larger version (23K): [in this window] [in a new window]   Figure 2. Effects of various Aß peptides on SMC viability using trypan blue exclusion assay. Number of dead MV SMC and aortic SMC is expressed as percentage of total cells after 3 days of peptide treatment (100 µg/mL). Data are mean and SD (bars) values of duplicate wells of 4 independent experiments. ***P<0.001 compared with control group by ANOVA with Bonferroni post hoc test.

View larger version (51K): [in this window] [in a new window]   Figure 3. [3H]Thymidine incorporation of MV SMC and aortic SMC after 3 days of Aß (Ab) peptide treatment (100 µg/mL). Counting of disintegrations per minute of the control group was considered 100%. Data are mean and SD (bars) values of triplicate wells from 4 independent experiments for MV SMC (A) and 3 independent experiments for aortic SMC (B). *P<0.05, ***P<0.001 compared with control group by ANOVA with Bonferroni test.

Aortic SMC also displayed an apparently greater response to E22Q-Aß than A21G- and Wt-Aß. The morphological changes of aortic SMC appeared after 2 to 3 days of incubation with E22Q-Aß but not with A21G-Aß, with Wt-Aß, or in the absence of Aß (Figure 4). These cells showed morphological changes similar to those of MV SMC when incubated with E22Q-Aß (Figures 1B and 4B). The E22Q-Aß–treated cells showed a significant reduction of cell viability compared with the control and A21G- and Wt-Aß groups (P<0.001) (Figure 2). There was no significant difference in percentage of dead aortic SMC treated with A21G- and Wt-Aß peptides compared with the control group. [³H]Thymidine incorporation was decreased only in aortic SMC treated by E22Q-Aß but not in cells exposed to A21G- and Wt-Aß (Figure 3B). This is consistent with the cell viability changes observed in these cells. In addition, we also compared the effect of each treatment on MV SMC with the effect of the same treatment on the aortic SMC. MV SMC exhibited a higher percentage of dead cells than aortic SMC (MV SMC, 36.9%; aortic SMC, 22.8%; P<0.05). [³H]Thymidine incorporation showed data consistent with results of cell viability studies in that E22Q-Aß caused a significant reduction of cell proliferation on MV SMC by comparison with aortic SMC (MV SMC, 16.0% of control; aortic SMC, 57.6% of control; P<0.001). There was no difference in the effect of A21G on cell viability and proliferation between MV and aortic SMC.

View larger version (129K): [in this window] [in a new window]   Figure 4. Morphological change of cultured human aorta-derived SMC exposed to various Aß1–40 peptides (100 µg/mL) for 3 days. A, Control. B, Dutch E22Q-Aß. C, Flemish A21G-Aß. D, Wt-Aß. Treatment with E22Q-Aß results in degeneration of aortic SMC. Magnification x30.

	Discussion

Top Abstract Introduction Subjects and Methods Results Discussion References Introduction

 
In this study we describe the effect of Aß peptide containing E22Q and A21G mutations on MV SMC and aortic SMC and also compare MV SMC with aortic SMC in their response to these Aß peptides. Our results show that E22Q-Aß peptide induced significantly decreased cellular proliferation and viability, as well as morphologically obvious degeneration of both MV and aortic SMC, whereas A21G-Aß and Wt-Aß did not exhibit significant toxicity with respect to these parameters. These results indicate a greater toxicity of E22Q-Aß with respect to MV-SMC and aortic SMC than that of A21G-Aß. This differential effect induced by E22Q- versus A21G-Aß on MV and aortic SMC represents an intriguing phenomenon because little documentation is available on clinicopathological features of patients carrying the Flemish A21G mutation. The precise mechanisms by which E22Q and A21G mutations at adjacent locations within the Aß sequence exhibit different effects on SMC are unclear. These effects may be linked to tissue- or cell type–specific metabolism and processing of mutant forms of Aß. A recent study indicated that Flemish APP692 and Dutch APP693 mutations have a different effect on Aß secretion as determined by cDNA transfection experiments in CHO-K1 cell lines.²² In vitro aggregation studies have also shown that Aß containing E22Q and A21G mutations differ in the kinetics of Aß fibril formation. E22Q mutant protein accelerates amyloid fibril formation, while the A21G mutant protein polymerizes more slowly than Wt-Aß,^{12 23 24 25} ie, the mutations might act by different pathological mechanisms or share another unknown property that distinguishes them from Wt-Aß. Further study of APP metabolism in vascular cells, such as SMC, transfected with DNA constructs corresponding to the APP693 and APP692 mutations will provide additional insights into the pathogenesis of Alzheimer disease and HCHWA-D–associated CAA.

Our study indicates that MV SMC exhibited obvious morphological changes after 3 days’ incubation with E22Q-Aß_1–40 (100 µg/mL) but not Wt-Aß_1–40. This is consistent with results described on leptomeningeal SMC.¹⁷ However, morphological changes of MV SMC appeared at an earlier stage and with lower peptide concentrations than those of leptomeningeal SMC in comparable experiments, suggesting that MV SMC are more sensitive to E22Q-Aß toxicity than are leptomeningeal SMC, although in our laboratory we have not made direct comparisons between leptomeningeal and parenchymal-derived SMCs. CAA-associated hemorrhage almost certainly occurs as a result of rupture of parenchymal rather than leptomeningeal blood vessels.^{2 10}

Vascular SMC have been reported to show heterogeneous histochemical, morphological, and growth phenotypes depending on their vessel of origin.^{18 19} However, in the present study comparison of SMC from microvessels and aorta in terms of their response to exogenous addition of Aß revealed that there seems to be no qualitatively distinct response to Wt Aß_1–40 and 2 mutated forms of Aß_1–40. From the statistical analysis used to compare the effect of each treatment between MV and aortic SMC, E22Q-Aß induced a more toxic effect on cell viability and proliferation of MV SMC than on aortic SMC, suggesting that MV SMC are more sensitive to E22Q-Aß than aortic SMC. The similar susceptibility of MV and aortic SMC to Aß toxicity is of interest in view of the strict localization of amyloid angiopathy to cerebral cortical and meningeal vessels, suggesting that SMC in intracranial vessels are distinct from those in extracranial vessels in terms of Aß metabolism. Decreased secretion and higher levels of cellular APP have been reported in cerebrovascular SMC compared with aortic SMC,²⁶ suggesting that this difference may contribute to the formation of Aß that is selectively deposited in the walls of cerebral cortical and meningeal vessels to produce symptomatic CAA.

	Acknowledgments

 
This study was supported by Public Health Service grants P30 AG 10123, P50 AG 16570, and P50 AG 12435. Dr Wang was supported in part by NIH training grant T32-NS-07356. Dr Natté was supported by Internationale Stichting Alzheimer Onderzoek (ISAO96506) and by the Dutch Organization of Scientific Research (NWO). We thank Professor Lynn Fairbanks for helpful discussions pertinent to statistical issues.

	Footnotes

 
Reprint requests to Harry V. Vinters, MD, Department of Pathology and Laboratory Medicine, UCLA School of Medicine, Room 18–170, CHS, Los Angeles, CA 90095-1732.

Received June 7, 1999; revision received November 11, 1999; accepted November 11, 1999.

	References

Top Abstract Introduction Subjects and Methods Results Discussion References Introduction

 

1. Kawai M, Kalaria RN, Cras P, Siedlak SL, Velasco ME, Shelton ER, Chan HW, Greenberg BD, Perry G. Degeneration of vascular smooth muscle cells in cerebral amyloid angiopathy of Alzheimer disease. Brain Res. 1993;623:142–146.[Medline] [Order article via Infotrieve]
2. Vinters HV, Wang ZZ, Secor DL. Brain parenchymal and microvascular amyloid in Alzheimer’s disease. Brain Pathol. 1996;6:179–195.[Medline] [Order article via Infotrieve]
3. Glenner GG, Wong CW. Alzheimer’s disease and Down’s syndrome: sharing of unique cerebrovascular amyloid fibril protein. Biochem Biophys Res Commun. 1984;122:1131–1135.[Medline] [Order article via Infotrieve]
4. Maat-Schieman MLC, van Duinen SG, Bornebroek M, Haan J, Roos RAC. Hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D), II: a review of histopathological aspects. Brain Pathol. 1996;6:115–120.[Medline] [Order article via Infotrieve]
5. Van Duinen SG, Castano EM, Bots GTAM, Luyendijk W, Frangione B. Hereditary cerebral hemorrhage with amyloidosis in patients of Dutch origin is related to Alzheimer disease. Proc Natl Acad Sci U S A. 1987;84:5991–5994.[Abstract/Free Full Text]
6. Vinters HV, Secor DL, Read SL, Frazee JG, Tomiyasu U, Stanley TM, Ferreiro JA, Akers M-A. Microvasculature in brain biopsy specimens from patients with Alzheimer’s disease: an immunohistochemical and ultrastructural study. Ultrastruct Pathol. 1994;18:333–348.[Medline] [Order article via Infotrieve]
7. Wisniewski HM, Fraçkowiak J, Zóltowska A, Kim KS. Vascular ß-amyloid in Alzheimer’s disease angiopathy is produced by proliferating and degenerating smooth muscle cells. Int J Exp Clin Invest. 1994;1:8–16.
8. Wisniewski HM, Wegiel J. ß-Amyloid formation by myocytes of leptomeningeal vessels. Acta Neuropathol (Berl). 1994;87:233–241.[Medline] [Order article via Infotrieve]
9. Natté R, Vinters HV, Maat-Schieman MLC, Bornebroek M, Haan J, Roos RAC, van Duinen SG. Microvasculopathy is associated with the number of cerebrovascular lesions in hereditary cerebral hemorrhage with amyloidosis, Dutch type. Stroke. 1998;29:1588–1594.[Abstract/Free Full Text]
10. Vinters HV, Natté R, Maat-Schieman MLC, Van Duinen SG, Hegeman-Kleinn I, Welling-Graafland C, Haan J, Roos RAC. Secondary microvascular degeneration in amyloid angiopathy of patients with hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D). Acta Neuropathol (Berl). 1998;95:235–244.[Medline] [Order article via Infotrieve]
11. Chartier-Harlin MC, Crawford F, Houlden H, Warren A, Hughes D, Fidani L, Goate A, Rossor M, Roques P, Hardy J, Mullan M. Early-onset Alzheimer’s disease caused by mutations at codon 717 of the ß-amyloid precursor protein gene. Nature. 1991; 353:844–846.
12. Haass C, Hung AY, Selkoe DJ, Teplow DB. Mutations associated with a locus for familial Alzheimer disease results in alternative processing of amyloid precursor protein. J Biol Chem. 1994;269:17741–17748.[Abstract/Free Full Text]
13. Hendriks L, van Duijn CM, Cras P, Cruts M, van Hul W, van Harskamp F, Warren A, McInnis MG, Antonarakis SE, Martin J J, Hofman A, van Broeckhoven C. Presenile dementia and cerebral hemorrhage linked to a mutation at codon 692 of the ß-amyloid precursor protein gene. Nature Genet. 1992;1:218–221.[Medline] [Order article via Infotrieve]
14. Lannfelt L, Bogdanovic N, Appelgren H, Axelman K, Lilius L, Hansson G, Schenk D, Hardy J, Winblad B. Amyloid precursor protein mutations causes Alzheimer’s disease in a Swedish family. Neurosci Lett. 1994;168:254–256.[Medline] [Order article via Infotrieve]
15. Murrel J, Farlow M, Ghetti B, Benson MD. A mutation in the amyloid precursor protein associated with hereditary Alzheimer’s disease. Science. 1991;254:97–99.[Abstract/Free Full Text]
16. Cras P, van Harskamp F, Hendriks L, Ceuterick C, van Duijn CM, Stefanko SZ, Hofman A, Kros JM, van Boreckhoven C, Martin JJ. Presenile Alzheimer dementia characterized by amyloid angiopathy and large amyloid core type senile plaques in the APP692 AlaGly mutation. Acta Neuropathol (Berl). 1998;96:253–260.[Medline] [Order article via Infotrieve]
17. Davis J, van Nostrand WE. Enhanced pathologic properties of Dutch-type mutant amyloid ß-protein. Proc Natl Acad Sci U S A. 1996;93:2996–3000.[Abstract/Free Full Text]
18. Cook BH, Granger HJ, Granger DN, Taylor AE, Smith EE. Metabolic profiles of canine cerebrovascular tree: a histochemical study. Stroke. 1978;9:165–168.[Abstract/Free Full Text]
19. Nakamura A, Isoyama S, Watanabe T, Katoh M, Sawai T. Heterogeneous smooth muscle cell populations derived from small and larger arteries. Microvasc Res. 1998;55:14–28.[Medline] [Order article via Infotrieve]
20. Vinters HV, Reave S, Costello P, Girvin JP, Moore SA. Isolation and culture of cells derived from human cerebral microvessels. Cell Tissue Res. 1987;249:657–667.[Medline] [Order article via Infotrieve]
21. Navab M, Hough GP, Stevenson LW, Drinkwater DC, Lakes H, Fogelman AM. Monocyte migration into the subendothelial space of a co-culture of adult human aortic endothelial and smooth muscle cells. J Clin Invest. 1988;82:1853–1863.
22. De Jonghe C, Zehr C, Yager D, Prada CM, Younkin S, Hendriks L, Van Broeckhoven C, Eckman CB. Flemish and Dutch mutations in amyloid ß precursor protein have different effects on amyloid ß secretion. Neurobiol Dis. 1998;5:281–286.[Medline] [Order article via Infotrieve]
23. Clements A, Walsh DM, Williams CH, Allsop D. Effects of the mutations Glu²² to Gln and Ala²¹ to Gly on the aggregation of a synthetic fragment of the Alzheimer’s amyloid ß/A4 peptide. Neurosci Lett. 1993;161:17–20.[Medline] [Order article via Infotrieve]
24. Walsh DM, Lomakin A, Benedek GB, Condron MM, Teplow DB. Amyloid beta-protein fibrillogenesis: detection of a protofibrillar intermediate. J Biol Chem. 1997;272:22364–22372.[Abstract/Free Full Text]
25. Wisniewski T, Ghiso J, Frangione B. Peptides homologous to the amyloid protein of Alzheimer disease containing a glutamine for glutamic acid substitution have accelerated amyloid fibril formation. Biochem Biophys Res Commun. 1991;179:1247–1254.[Medline] [Order article via Infotrieve]
26. van Nostrand WE, Rozemuller AJM, Chung R, Cotman CW, Saporito-Irwin SM. Amyloid ß-protein precursor in cultured leptomeningeal smooth muscle cells. Int J Exp Clin Invest. 1994;1:1–8.

Editorial Comment

William I. Rosenblum, MD, Guest Editor

Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia

	Introduction

Top Abstract Introduction Subjects and Methods Results Discussion References Introduction

 
The deposition of amyloid in the wall of cerebral blood vessels is an important correlate of vascular damage and of cerebral hemorrhage in elderly patients in which the wild type of ß-A4 amyloid is the protein in question and in a hereditary form of cerebral amyloid angiopathy. In the latter, Dutch type, one or another mutated form of ß-A4 is produced and deposited in the vessel wall. The Dutch type is the disease dealt with in this report.

The authors test the hypothesis that the amyloid is toxic to vascular smooth muscle. The test was performed using cultured smooth muscle cells exposed to 1 of 3 types of ß-A4 peptide. The wild type had no significant adverse effects, nor did 1 of 2 mutated forms of the peptide found in the Dutch type of hereditary disease. However, the other mutated form found in that disease did, indeed, damage the smooth muscle from either cerebral cortical microvessels or from aorta.

These findings present the authors and their readers with an unsolved interpretive dilemma. Why weren’t both mutated forms toxic? In view of that fact, is it possible that the results are not relevant to the disease? One possibility is that the toxicity observed here is unrelated to the mechanism of in vivo damage. For example, could the deposition of amyloid in the vessel wall be a secondary result of some other metabolic defect that would lead, even without the amyloid, to alteration of the wall, rupture, and hemorrhage? A second possibility is that conditions in tissue culture do not permit meaningful analysis of the mechanisms underlying the vascular damage produced by amyloid in vivo. Both types of amyloid may be vasotoxic, but their true mechanism of action could not be brought into play under these experimental conditions.

Received June 7, 1999; revision received November 11, 1999; accepted November 11, 1999.

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wang, Z. Articles by Rosenblum, W. I. Search for Related Content PubMed PubMed Citation Articles by Wang, Z. Articles by Rosenblum, W. I. Pubmed/NCBI databases Substance via MeSH Related Collections Smooth muscle proliferation and differentiation Intracerebral Hemorrhage Pathology of Stroke Genetics of cardiovascular disease