| 1. |
- Enge, Maria, 1970, et al.
(author)
-
Endothelium-specific platelet-derived growth factor-B ablation mimics diabetic retinopathy.
- 2002
-
In: The EMBO journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 21:16, s. 4307-16
-
Journal article (peer-reviewed)abstract
- Loss of pericytes from the capillary wall is a hallmark of diabetic retinopathy, however, the pathogenic significance of this phenomenon is unclear. In previous mouse gene knockout models leading to pericyte deficiency, prenatal lethality has so far precluded analysis of postnatal consequences in the retina. We now report that endothelium-restricted ablation of platelet-derived growth factor-B generates viable mice with extensive inter- and intra-individual variation in the density of pericytes throughout the CNS. We found a strong inverse correlation between pericyte density and the formation of a range of retinal microvascular abnormalities strongly reminiscent of those seen in diabetic humans. Proliferative retinopathy invariably developed when pericyte density was <50% of normal. Our data suggest that a reduction of the pericyte density is sufficient to cause retinopathy in mice, implying that pericyte loss may also be a causal pathogenic event in human diabetic retinopathy.
|
|
| 2. |
- Betsholtz, Christer, 1959, et al.
(author)
-
Role of platelet-derived growth factor in mesangium development and vasculopathies: lessons from platelet-derived growth factor and platelet-derived growth factor receptor mutations in mice.
- 2004
-
In: Current opinion in nephrology and hypertension. - 1062-4821. ; 13:1, s. 45-52
-
Journal article (peer-reviewed)abstract
- PURPOSE OF REVIEW: The phenotypic consequences of null mutations in the platelet-derived growth factor-B and the platelet-derived growth factor beta-receptor genes in mice have demonstrated that these proteins play pivotal roles in the development of the vascular smooth muscle cell lineage, including pericytes and mesangial cells. RECENT FINDINGS: The lethality of these mutants has precluded analysis of the physiological and pathophysiological consequences of platelet-derived growth factor-B and platelet-derived growth factor beta-receptor deficiency in adults. This review summarizes and discusses recent data from certain tissue-specific and subtle mutations in the platelet-derived growth factor-B and platelet-derived growth factor beta-receptor genes that are compatible with postnatal viability in spite of severe developmental deficits in pericyte and mesangial cell recruitment. In the postnatal period, the animals studied developed a characteristic set of pathological changes to small blood vessels of the retina and the kidney glomerulus, which sheds light on the importance of pericytes and mesangial cells for vascular integrity and function after birth. SUMMARY: These microvascular abnormalities and their consequences bear a resemblance to diabetic microangiopathy and nephropathy. The platelet-derived growth factor-B and platelet-derived growth factor beta-receptor mutant mouse models, therefore, might serve as valuable tools in the dissection of some of the pathogenic events in diabetic microangiopathy.
|
|
| 3. |
- Bjarnegård, Mattias, 1970, et al.
(author)
-
Endothelium-specific ablation of PDGFB leads to pericyte loss and glomerular, cardiac and placental abnormalities
- 2004
-
In: DEVELOPMENT. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 131:8, s. 1847-1857
-
Journal article (peer-reviewed)abstract
- Platelet-derived growth factor-B (PDGFB) is necessary for normal cardiovascular development, but the relative importance of different cellular sources of PDGFB has not been established. Using Cre-lox techniques, we show here that genetic ablation of Pdgfb in endothelial cells leads to impaired recruitment of pericytes to blood vessels. The endothelium-restricted Pdgfb knockout mutants also developed organ defects including cardiac, placental and renal abnormalities. These defects were similar to those observed in Pdgfb null mice. However, in marked contrast to the embryonic lethality of Pdgfb null mutants, the endothelium-specific mutants survived into adulthood with persistent pathological changes, including brain microhemorrhages, focal astrogliosis, and kidney glomerulus abnormalities. This spectrum of pathological changes is reminiscent of diabetic microangiopathy, suggesting that the endothelium-restricted Pdgfb knockouts may serve as models for some of the pathogenic events of vascular complications to diabetes. Key words: PDGFB, Endothelium, Cre, loxP, Pericytes, Microaneurysm
|
|
| 4. |
- Bjarnegård, Mattias, 1970
(author)
-
Effects of PDGF-B gene inactivation in endothelial cell
- 2004
-
Doctoral thesis (other academic/artistic)abstract
- Platelet-derived growth factor-B (PDGF-B) is expressed by endothelial cells, neurons, macrophages and platelets. The relative importance of these cellular PDGF-B sources in vivo has been addressed by the creation of a conditional PDGF-B allele, which in the presence of a specific recombinase can be silenced in different tissues. Endothelium-specific PDGF-B ablation leads to defective pericyte recruitment to growing and branching blood vessels. In the embryo, this results in abnormalities such as kidney glomeruli devoid of mesangial cells, heart dilation, placenta abnormalities, spontaneous bleedings, microaneurysms and lowered capillary density in the central nervous system (CNS). All these changes are common to both the endothelium-specific and the full PDGF-B knock-out, but the former presents a variable and slightly milder phenotype, due to an incomplete recombination process. The resulting cellular mosaicism allows for postnatal survival, and thereby studies of adult PDGF-B functions.Many of the embryonic phenotypes seen in endothelium-specific PDGF-B knock-out mice normalized postnatally, but certain pathological changes persisted and even became aggravated in the adult animals. We conclude that: Endothelial cells are the most important source of PDGF-B, and this source is crucial for pericyte recruitment. The pericyte density directly reflects the level of endothelium-produced PDGF-B. The defective pericyte recruitment is probably the cause of all organ defects seen in the endothelium-specific PDGF-B knock-outs, including placenta and heart defects. The pericyte deficiency leads to a spectrum of vascular defects which mimics diabetic micro-angiopathy. The retina is particularly sensitive to pericyte deficiency. When the density falls below 50% of normal, the retinopathy changes from a non-proliferative to a proliferative state, similar to the progression at diabetic retinopathy. Endothelium-derived PDGF-B is important for kidney glomerular function as endothelium-specific PDGF-B knock-outs develop proteinuria in morphologically normal kidneys
|
|
| 5. |
- Gullberg, Mats, et al.
(author)
-
Cytokine detection by antibody-based proximity ligation
- 2004
-
In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 101:22, s. 8420-4
-
Journal article (other academic/artistic)abstract
- Efficient and precise detection techniques, along with extensive repertoires of specific binding reagents, will be needed to meet the challenges of proteome analyses. The recently established proximity ligation mechanism enables sensitive high-capacity protein measurements by converting the detection of specific proteins to the analysis of DNA sequences. Proximity probes containing oligonucleotide extensions are designed to bind pairwise to target proteins and to form amplifiable tag sequences by ligation when brought in proximity. In our previous report, both the ligatable arms and the protein binders were DNA molecules. We now generalize the method by providing simple and convenient protocols to convert any polyclonal antibodies or matched pair of monoclonal antibodies to proximity probe sets through the attachment of oligonucleotide sequences. Sufficient reagent for >100,000 proximity ligation assays can be prepared from 1 microg of antibody. The technique is applied to measure cytokines in a homogenous test format with femtomolar detection sensitivities in 1-microl samples, and we exemplify its utility in situations when only minute sample amounts are available.
|
|
| 6. |
- Nyström, Henrik, 1977, et al.
(author)
-
Platelet-derived growth factor B retention is essential for development of normal structure and function of conduit vessels and capillaries
- 2006
-
In: Cardiovasc Res. - : Oxford University Press (OUP). - 0008-6363. ; 71:3, s. 557-65
-
Journal article (peer-reviewed)abstract
- OBJECTIVE: Extracellular retention of PDGF-B has been proposed to play an important role in PDGF-B signalling. We used the PDGF-B retention motif knockout mouse (RetKO) to study the effects of retention motif deletion on development of micro- and macrovascular structure and function. METHODS: Passive and active properties of conduit vessels were studied using myograph techniques and histological examination. Capillary structure and function was studied using measurements of capillary density in skeletal muscle and by assessing aerobic physical performance in a treadmill setup. Cardiac function was assessed using echocardiography. RESULTS: Myograph experiments revealed an increased diameter and stiffness of the aorta in RetKO. Histological examination showed increased media collagen content and a decreased number of aortic wall layers, however with a similar number of vascular smooth muscle cells. This outward eutrophic remodelling of the aorta was accompanied by endothelial dysfunction. RetKO showed decreased capillary density in skeletal muscle and signs of a defective delivery of capillary oxygen to skeletal muscle, as shown by a decreased physical performance. In RetKO mice, echocardiography revealed an adaptive eccentric cardiac hypertrophy. CONCLUSION: We conclude that retention of PDGF-B during development is essential for a normal conduit vessel function in the adult mouse. Furthermore, PDGF-B retention is also necessary for the development of an adequate capillary density, and thereby for a normal oxygen delivery to skeletal muscle. The lack of primary effects on cardiac function supports the redundant role of PDGF-B in cardiac development.
|
|
| 7. |
|
|
