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Record W7132896953

Retinal Stem Cells: Expansion and Progeny Characterization

2021· dissertation· W7132896953 on OpenAlexaff
Tahani Baakdhah

Bibliographic record

VenueTSpace · 2021
Typedissertation
Language
FieldBiochemistry, Genetics and Molecular Biology
TopicRetinal Development and Disorders
Canadian institutionsUniversity of Toronto
Fundersnot available
KeywordsExtracellular matrixStem cellRetinal pigment epitheliumMulticellular organismChromatin structure remodeling (RSC) complexCellular differentiationIn vivoCell culture
DOInot available

Abstract

fetched live from OpenAlex

Growing retinal stem cell (RSC) clonal spheres in traditional static culture is associated with low expansion rate and poor survival attributed to loss of cells during the enzymatic dissociation steps. Another problematic issue is the difficulty to mimic in vivo stem cell niche conditions. Using our traditional lab protocol, only 0.2% of the pigmented ciliary epithelium cells (CE) give rise to floating RSC clonal spheres in serum free conditions. These issues have hindered our ability to study the signaling pathways governing RSC proliferation and expansion in vitro. To overcome these limitations, I used microcarriers (MCs) in a suspension stirring bioreactor (SSB) to help achieve sufficient numbers suitable for differentiation and transplantation. Using this new protocol, I achieved a significant (10-fold) enrichment of RSC yield compared to conventional static culture techniques using a combination of FACTIII MCs and relative hypoxia (5%) inside the bioreactor. My work showed that hypoxia (5% O2) was associated with better RSC expansion across all platforms which was attributed to hypoxia-induced boosting survival and/or symmetric division of stem cells. RSC spheres were thought to be unvaried and were randomly picked and placed on laminin extracellular matrix (ECM) in static plates. In my work, I found noticeable variance in the pigment distribution between RSC spheres which led me to categorize them into three different groups according to their pigmentation, I also noted that this variance in pigment level and distribution was associated with contrasting differentiation potentials. RSCs were classified into three morphological groups: heavily pigmented (HP), lightly pigmented (LP) and centrally pigmented (CP) spheres. Unlike the other two sphere types, CP spheres were capable of producing highly proliferative progenitors (producing large number of cobblestone-like cell lawns) in adherent culture that differentiate into retinal pigment epithelium (RPE) cells. I found that the individual stem cells that (clonally) formed the three sphere types appear homogeneous, but it is their downstream progenitors that are different. I showed that CP spheres contain a population of early RPE progenitors that respond to proliferative signals from the surrounding non-pigmented neural retinal cells while The HP and LP spheres do not respond to these signals.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesMeta-epidemiology (narrow)
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: Bench or experimental
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.101
Threshold uncertainty score1.000

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0010.001
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0010.000
Insufficient payload (model declined to judge)0.0000.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.009
GPT teacher head0.269
Teacher spread0.259 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one teacher head, not a consensus.

Study designBench or experimental
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations0
Published2021
Admission routes1
Has abstractyes

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