RNA-based Reprogramming of Human Primary Fibroblasts into Induced Pluripotent Stem Cells
November 26th, 2018
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Here we describe a clinically relevant, high-efficiency, feeder-free method to reprogram human primary fibroblasts into induced pluripotent stem cells using modified mRNAs encoding reprogramming factors and mature microRNA-367/302 mimics. Also included are methods to assess reprogramming efficiency, expand clonal iPSC colonies, and confirm expression of the pluripotency marker TRA-1-60.
Overview
This article presents a high-efficiency, feeder-free method for reprogramming human primary fibroblasts into induced pluripotent stem cells (iPSCs) using modified mRNAs and microRNA mimics. The protocol includes methods for assessing reprogramming efficiency, expanding iPSC colonies, and confirming pluripotency marker expression.
Key Study Components
Area of Science
- Stem Cell Biology
- Cell Reprogramming
- Regenerative Medicine
Background
- Induced pluripotent stem cells (iPSCs) are valuable for studying human diseases.
- High-quality, integration-free iPSCs can be generated from challenging fibroblast sources.
- Optimizing transfection efficiency is crucial for successful reprogramming.
- pH adjustment of transfection buffers is a key step in the protocol.
Purpose of Study
- To develop a reliable method for generating iPSCs from human fibroblasts.
- To enhance the efficiency of reprogramming protocols.
- To provide a detailed methodology for researchers in the field.
Methods Used
- Preparation of transfection buffer with optimal pH.
- Coating plates with recombinant human laminin for cell attachment.
- Transfection of fibroblasts with modified mRNAs and microRNA mimics.
- Assessment of reprogramming efficiency and iPSC colony expansion.
Main Results
- Successful generation of high-quality iPSCs from various fibroblast types.
- Demonstrated the importance of pH in transfection buffer for optimal results.
- Confirmed expression of pluripotency markers in reprogrammed cells.
- Provided a scalable method for iPSC production.
Conclusions
- This method offers a significant advancement in iPSC technology.
- It is applicable to difficult-to-reprogram fibroblast sources.
- Future applications include disease modeling and stem cell therapies.
Frequently Asked Questions
What are induced pluripotent stem cells (iPSCs)?
iPSCs are stem cells that can be generated directly from adult cells and have the ability to differentiate into any cell type.
Why is pH adjustment important in this protocol?
Adjusting the pH of the transfection buffer optimizes RNA transfection efficiency, which is critical for successful reprogramming.
What is the significance of using microRNA mimics?
MicroRNA mimics enhance the reprogramming process by promoting pluripotency and improving the efficiency of iPSC generation.
Can this method be used for aged fibroblasts?
Yes, this protocol is designed to efficiently reprogram difficult-to-reprogram fibroblasts, including those from aged individuals.
What markers are used to confirm pluripotency?
The expression of pluripotency markers such as TRA-1-60 is assessed to confirm the successful reprogramming of fibroblasts into iPSCs.
How does this method compare to traditional reprogramming techniques?
This method is feeder-free and offers higher efficiency and quality of iPSCs compared to traditional techniques that often involve viral integration.
Executive Industry Relevance
This protocol enables high-efficiency, integration-free reprogramming of human fibroblasts into iPSCs, addressing a critical bottleneck in disease modeling and regenerative therapy development. By generating high-quality iPSCs from difficult-to-reprogram sources such as aged, diseased, or senescent fibroblasts, the method enhances target validation and de-risks translational pipelines. The non-viral, mRNA-based approach supports scalable, GMP-compatible workflows for preclinical and clinical applications.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of disease mechanisms using patient-derived iPSCs from historically refractory fibroblast sources.
- Operational Value: Provides a consistent, high-efficiency source of pluripotent cells for target de-risking and pathway analysis.
- Predictive Value: Supports early assessment of therapeutic hypotheses in genetically relevant human cellular models.
Screening & Assay Development
- Scientific Value: Generates standardized, feeder-free iPSC populations suitable for reproducible phenotypic and chemical screening assays.
- Operational Value: Enables scalable production of isogenic iPSC lines for assay standardization across screening campaigns.
- Predictive Value: Improves confidence in hit-to-lead progression by reducing variability from cellular heterogeneity.
Translational & Preclinical Research
- Scientific Value: Facilitates disease-relevant modeling using iPSCs derived from aged or pathogenic fibroblast donors.
- Operational Value: Supports seamless transition from discovery to preclinical validation through defined, xeno-free culture conditions.
- Predictive Value: Enhances preclinical predictability by enabling correction of genetic defects and isogenic control generation.
Pipeline & Workflow Integration
The method fits within the discovery continuum from target validation through lead identification to preclinical efficacy testing, particularly for diseases involving fibroblast dysfunction or aging-related pathology.
- Discovery Biology: Enables functional validation of disease-associated genes in reprogrammed human cells with defined genetic background.
- Screening: Produces transfection-optimized iPSCs amenable to high-content and high-throughput assay formats.
- Analytics: Delivers quantitative pluripotency readouts (e.g., TRA-1-60+) to assess reprogramming success and clonal consistency.
- Translational Research: Supports continuity from fibroblast reprogramming to differentiation into disease-relevant somatic cells for mechanism elucidation.
- Enterprise Reuse: Establishes a reusable, standardized platform for iPSC generation across multiple projects and disease areas.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in target validation by reducing noise from incomplete reprogramming or genomic instability.
- Operational Value: Delivers reproducible, high-efficiency iPSC production with minimal batch-to-batch variability.
- Strategic Value: Reduces attrition risk in early programs by enabling rigorous human cellular model-based go/no-go decisions.
- Portfolio Impact: Accelerates advancement of promising candidates through improved disease model fidelity and mechanistic de-risking.
Implementation Considerations
- Requires expertise in RNA handling, transfection optimization, and stem cell culture.
- Depends on access to modified mRNA synthesis, microRNA mimics, and transfection reagents.
- Necessitates standardized pH adjustment and filtration of transfection buffer for consistent performance.
- Requires adaptation for varying fibroblast confluency, passage number, and donor variability.
- Limited by the need for frequent transfections (every 48 h) and careful monitoring of cytotoxicity.
Biopharma FAQs
Why does pH adjustment of transfection buffer matter for RNA delivery?
Adjusting the transfection buffer to pH 8.15–8.17 optimizes the efficiency of modified mRNA and microRNA mimic delivery into fibroblasts, which is critical for achieving high reprogramming efficiency. This step ensures maximal RNA transfection efficiency, directly impacting the success of iPSC generation.
How does transfection regimen frequency influence reprogramming outcomes?
Transfecting fibroblasts with modified mRNAs and microRNA mimics every 48 hours over two weeks sustains pluripotency factor expression necessary for reprogramming. This regimen supports consistent iPSC colony formation, particularly in difficult-to-reprogram cell sources.
What role do microRNA-367/302 mimics play in the reprogramming process?
MicroRNA-367/302 mimics enhance reprogramming efficiency by promoting pluripotency and overcoming cellular barriers when co-delivered with pluripotency factor-encoding modified mRNAs. Their inclusion improves the speed and robustness of iPSC colony formation.
Why is fibroblast seeding density critical for reprogramming success?
Seeding fibroblasts at 40–60% confluency ensures optimal cell attachment and transfection efficiency; suboptimal density leads to poor colony formation or acellular patches. Proper density supports uniform reprogramming and reduces variability across experiments.
What pluripotency marker is used to confirm reprogramming efficiency in this protocol?
Expression of TRA-1-60 is assessed via immunostaining to confirm successful reprogramming of fibroblasts into iPSCs. High TRA-1-60 positivity correlates with high-quality, fully reprogrammed iPSC colonies.
