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Updated: Jul 7, 2026
Enrichment of Bruch's Membrane from Human Donor Eyes
Published on: November 15, 2015
Morphometric analysis of lipoprotein-like particle accumulation in aging human macular Bruch's membrane
Jiahn-Dar Huang1, Christine A Curcio, Mark Johnson
1Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208-3107, USA.
Purpose:
To determine the size and regional distribution of lipoprotein-like particles (LLPs) that accumulate with age in Bruch's membrane (BrM).
Methods:
The quick-freeze/deep-etch method was used to prepare specimens of human BrM (age range, 27-78) for electron microscopic examination. Stereologic methods were used to analyze the resultant micrographs and determine the age-related changes of the LLP volume fraction and diameter distribution in various locations in BrM.
Results:
The volume fraction occupied by LLPs was found to increase monotonically with age in both the inner collagenous layer (ICL) and elastic layer (EL), but not in the outer collagenous layer (OCL). The mass of total LLP-associated lipids in BrM also increased with age. There was no significant increase in LLP size with age, but there was a modest increase in size with increased volume fraction of LLPs in BrM.
Conclusions:
The pattern of accumulation of particles was consistent with a retinal pigment epithelium (RPE) source for the LLPs, which explains why once the EL and ICL were filled with particles, LLPs continued to accumulate near the RPE, but no further accumulation was found in the OCL. The quantity of LLP-associated lipids found in BrM accounts for a large portion of the accumulated lipids measured in this tissue.
Insights
Lipoprotein-like particles (LLPs) accumulate with age in Bruch's membrane (BrM), primarily in the inner and elastic layers. This accumulation, linked to retinal pigment epithelium (RPE) cells, contributes significantly to age-related lipid buildup in BrM.
Area of Science:
- Ophthalmology
- Cell Biology
- Biochemistry
Background:
- Bruch's membrane (BrM) is a crucial layer in the retina.
- Age-related changes in BrM contribute to vision impairment.
- Lipoprotein-like particles (LLPs) are implicated in BrM pathology.
Purpose of the Study:
- To quantify the size and distribution of age-accumulated lipoprotein-like particles (LLPs) within Bruch's membrane (BrM).
- To investigate the regional differences in LLP accumulation in BrM.
- To correlate LLP accumulation with age-related changes in BrM.
Main Methods:
- Human BrM specimens (ages 27-78) were prepared using quick-freeze/deep-etch electron microscopy.
- Stereologic analysis was employed to quantify LLP volume fraction and diameter.
- Regional analysis was performed across different BrM layers (ICL, EL, OCL).
Main Results:
- LLP volume fraction increased with age in the inner collagenous layer (ICL) and elastic layer (EL), but not the outer collagenous layer (OCL).
- Total LLP-associated lipid mass in BrM increased with age.
- LLP size did not significantly increase with age, but showed modest growth with higher LLP volume.
Conclusions:
- The accumulation pattern suggests a retinal pigment epithelium (RPE) origin for LLPs.
- LLPs fill the EL and ICL before accumulating near the RPE, explaining the lack of OCL accumulation.
- LLP-associated lipids constitute a major component of age-related lipid accumulation in BrM.
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