Regenerative Medicine Engineering

🦠Regenerative Medicine Engineering Unit 2 – Cell Biology Fundamentals

Cell biology fundamentals form the foundation of regenerative medicine engineering. This unit covers key concepts like cell structure, cellular processes, and stem cell biology. Understanding these basics is crucial for developing innovative therapies to repair or replace damaged tissues. The unit explores cell communication, division, and differentiation, which are essential for tissue engineering and stem cell therapy. It also delves into cellular applications in regenerative medicine, including organoids and gene editing, while addressing challenges and future directions in the field.

Key Concepts and Terminology

  • Cell theory states all living organisms are composed of cells, the basic unit of life
  • Prokaryotic cells lack a membrane-bound nucleus and organelles (bacteria)
  • Eukaryotic cells contain a membrane-bound nucleus and organelles (animals, plants)
  • Cellular differentiation process by which a less specialized cell becomes more specialized
  • Totipotency ability of a cell to give rise to all cell types of an organism
  • Pluripotency capacity of a cell to differentiate into multiple cell types
  • Multipotency ability of a cell to differentiate into a limited number of cell types
  • Unipotency capacity of a cell to differentiate into only one cell type

Cell Structure and Organization

  • Plasma membrane separates the cell interior from the external environment
    • Composed of a phospholipid bilayer with embedded proteins
    • Regulates the transport of molecules in and out of the cell
  • Cytoskeleton provides structural support and enables cell movement
    • Consists of microfilaments, intermediate filaments, and microtubules
  • Nucleus contains the cell's genetic material (DNA) and controls cellular activities
  • Endoplasmic reticulum (ER) site of protein and lipid synthesis
    • Rough ER studded with ribosomes for protein synthesis
    • Smooth ER lacks ribosomes and is involved in lipid synthesis and detoxification
  • Golgi apparatus modifies, packages, and sorts proteins for secretion or transport
  • Mitochondria generate energy (ATP) through cellular respiration
  • Lysosomes contain digestive enzymes that break down cellular waste and foreign particles

Cellular Processes and Functions

  • Metabolism encompasses all chemical reactions that occur within a cell
    • Catabolism breaks down complex molecules to release energy
    • Anabolism synthesizes complex molecules from simpler ones, requiring energy
  • Cellular respiration process that converts glucose into ATP in the presence of oxygen
    • Glycolysis breaks down glucose into pyruvate in the cytoplasm
    • Citric acid cycle oxidizes pyruvate to produce NADH and FADH2 in the mitochondria
    • Electron transport chain creates a proton gradient to drive ATP synthesis
  • Photosynthesis process by which plants convert light energy into chemical energy
  • Protein synthesis involves transcription (DNA to RNA) and translation (RNA to protein)
    • Ribosomes serve as the site of protein synthesis
  • DNA replication process by which a cell duplicates its genetic material before division
  • RNA processing includes splicing, capping, and polyadenylation to produce mature mRNA

Cell Communication and Signaling

  • Cells communicate through direct contact or by secreting signaling molecules
  • Ligands (hormones, neurotransmitters) bind to specific receptors on the target cell
  • Receptors can be located on the cell surface or within the cell (intracellular receptors)
  • Signal transduction pathways relay the signal from the receptor to effector molecules
    • G protein-coupled receptors (GPCRs) activate intracellular signaling cascades
    • Receptor tyrosine kinases (RTKs) initiate signaling through phosphorylation
  • Second messengers (cAMP, calcium) amplify and propagate the signal within the cell
  • Cell signaling regulates various cellular processes (proliferation, differentiation, apoptosis)
  • Dysregulation of cell signaling can lead to diseases (cancer, autoimmune disorders)

Cell Division and Reproduction

  • Cell cycle consists of interphase (G1, S, G2) and mitosis (M)
    • G1 phase cell grows and prepares for DNA replication
    • S phase DNA replication occurs
    • G2 phase cell prepares for mitosis
    • M phase cell divides into two daughter cells
  • Mitosis division of the nucleus into two genetically identical nuclei
    • Prophase chromosomes condense, nuclear envelope breaks down
    • Metaphase chromosomes align at the equatorial plane
    • Anaphase sister chromatids separate and move towards opposite poles
    • Telophase nuclear envelopes reform around the separated chromosomes
  • Cytokinesis division of the cytoplasm to form two separate daughter cells
  • Meiosis cell division that produces haploid gametes (sperm, egg) for sexual reproduction
    • Meiosis I homologous chromosomes separate, resulting in two haploid cells
    • Meiosis II sister chromatids separate, resulting in four haploid cells

Stem Cells and Differentiation

  • Stem cells unspecialized cells capable of self-renewal and differentiation
  • Embryonic stem cells (ESCs) derived from the inner cell mass of a blastocyst
    • Pluripotent can differentiate into all cell types of the body
  • Adult stem cells found in various tissues (bone marrow, skin, gut)
    • Multipotent can differentiate into a limited number of cell types
  • Induced pluripotent stem cells (iPSCs) generated by reprogramming somatic cells
  • Stem cell niche specialized microenvironment that regulates stem cell behavior
  • Differentiation triggered by specific signals (growth factors, cytokines)
    • Lineage commitment process by which a stem cell becomes restricted to a specific fate
  • Transcription factors (Oct4, Sox2, Nanog) maintain pluripotency in ESCs

Cellular Applications in Regenerative Medicine

  • Stem cell therapy involves transplanting stem cells to repair or replace damaged tissues
    • Hematopoietic stem cell transplantation treats blood disorders (leukemia)
    • Mesenchymal stem cells (MSCs) used for tissue regeneration (cartilage, bone)
  • Tissue engineering combines stem cells, scaffolds, and growth factors to create functional tissues
  • Organoids three-dimensional, miniaturized organs grown from stem cells
    • Used for disease modeling, drug screening, and personalized medicine
  • Cell reprogramming converts somatic cells into iPSCs or directly into other cell types
  • Gene therapy introduces functional genes into cells to correct genetic defects
  • Genome editing (CRISPR-Cas9) precisely modifies the genome of cells for therapeutic purposes

Challenges and Future Directions

  • Ethical concerns surrounding the use of embryonic stem cells and gene editing
  • Immunogenicity and rejection of transplanted cells or tissues
  • Tumorigenicity potential of stem cells to form tumors after transplantation
  • Scalability and cost of producing large quantities of high-quality cells for therapy
  • Delivery and integration of cells or tissues into the target site
  • Long-term safety and efficacy of cell-based therapies
  • Regulatory hurdles and clinical translation of regenerative medicine approaches
  • Personalized medicine tailoring therapies to individual patient needs and genetics
  • Combination therapies integrating stem cells, biomaterials, and growth factors for optimal regeneration


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© 2024 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.