Wound Healing & Regenerative Medicine – Prof. Dr. Martijn van Griensven (RMT1006 2024-2025)

A comprehensive set of Q&A flashcards covering wound-healing stages, molecular regulators, scarring, fetal versus adult differences, cell interactions (cadherins, integrins), EMT, skin and corneal tissue engineering requirements, current therapies, and future regenerative medicine strategies.

What are the four overlapping stages of adult skin wound healing?

Hemostasis, Inflammation, Proliferation (granulation & contraction), and Maturation/Remodelling.

During which stage do neutrophils and monocytes dominate and perform phagocytosis?

Inflammatory stage of wound healing (minutes/hours to 3-4 days).

Which two cell types drive re-epithelialisation and re-vascularisation in the proliferative phase?

Keratinocytes (re-epithelialisation) and endothelial cells (re-vascularisation).

Why is vascularisation critical in tissue engineering beyond ~100–200 µm?

Oxygen diffusion is limited to ~100–200 µm; beyond this, new blood vessels must form to prevent hypoxia.

Which major growth factor family orchestrates cell migration, matrix remodelling and myofibroblast differentiation in adult skin healing?

TGF-β superfamily.

Name three additional pro-healing cytokines/growth factors besides TGF-β mentioned in the lecture.

Connective Tissue Growth Factor (CTGF), Vascular Endothelial Growth Factor (VEGF), Fibroblast Growth Factor (FGF) or Platelet-Derived Growth Factor (PDGF).

What are the two main classes of wound closure and how do they differ?

Primary healing: all layers closed, minimal scar; Secondary healing: deep layers closed, superficial left open to heal inside-out, more scarring.

List three key differences between fetal and adult skin wound healing.

Fetal: faster re-epithelialisation, minimal inflammation, predominantly collagen III with high hyaluronic acid; Adult: slower epithelialisation, pronounced inflammation, collagen I rich scars.

Up to which gestational week is human fetal skin able to heal scar-free?

Approximately the first 24 weeks of gestation.

Which cytokine isoform is elevated in fetal wounds and associated with scarless healing?

TGF-β3 (relative increase vs. TGF-β1 and TGF-β2).

What are the principal cell-adhesion molecules forming adherens junctions between epithelial cells?

Classical cadherins (E-cadherin, N-cadherin, etc.).

Which receptors mediate cell-ECM binding at focal adhesions and hemidesmosomes?

Integrins.

Name the three major classes of extracellular matrix molecules.

Structural proteins (collagen, elastin), proteoglycans, and adhesive glycoproteins (fibronectin, laminin).

What property of integrins can be increased by clustering (‘inside-out’ signalling)?

Avidity (overall adhesiveness/affinity of integrin binding).

Which five fundamental cellular mechanisms are driven by cytokines, cadherins and integrins during wound healing?

Cell adhesion, migration, proliferation & survival, apoptosis (anoikis), and differentiation (including EMT).

Define epithelial-to-mesenchymal transition (EMT) in the context of wound repair.

A process where epithelial cells lose polarity and junctions, gain motility, and adopt mesenchymal phenotype to migrate and rebuild tissue.

What ECM change triggers keratinocyte motility during skin repair?

Loss of E-cadherin and altered ECM composition at the wound edge.

Give two common pathological scar types characterised by raised tissue.

Hypertrophic scars and keloid scars.

Which factors can increase the extent of scarring?

Wound location, size, depth, infection, tension, and individual predisposition.

What is the principal goal of modern skin tissue engineering?

Create constructs that mimic natural skin’s multi-layered structure, barrier function, regenerative capacity, and minimal scarring.

Name three desired material properties for engineered skin substitutes listed in the lecture.

Semi-permeable barrier, antibacterial/waterproof, immune modulation (others include UV protection, thermoregulation, sensory capability, rapid self-repair).

What three core components are ‘required for regenerating skin’?

Spatial information for self-organisation, stem cells, and extracellular matrix.

List four practical requirements for clinical skin TE constructs (e.g., surgeon’s perspective).

Rapid availability, affordable, autologous (or low immunogenicity), reliable wound adherence (others: site-matched, minimal donor morbidity, manageable, improved scar).

Give one advantage and one limitation of current polymeric nanofibre skin scaffolds.

Advantage: biocompatible and can carry bioactive compounds; Limitation: lack of fat layer, pigmentation mismatch, potential contraction and scarring.

Which two strategies to reduce scar formation were highlighted?

Dampening excessive inflammation and limiting myofibroblast presence/activity.

Why is corneal wound healing clinically significant?

Corneal haze or scarring can lead to blindness; current transplantation success is limited.

Where are corneal epithelial stem cells located?

In the limbus (limbal stem cells).

Which ECM proteins appear only in wounded corneal epithelium and guide adhesion/migration?

Fibronectin, tenascin C, and vitronectin.

Name two growth factors released in the cornea that promote limbal stem cell proliferation.

KGF (from limbal fibroblasts) and EGF or FGF-β (from damaged epithelium).

What is the current gold-standard surgical treatment for severe corneal opacity?

Corneal transplantation (keratoplasty).

Give two examples of artificial corneas (keratoprostheses).

Boston KPro (PMMA) and AlphaCor KPro (PHEMA).

State four key material requirements for an artificial cornea.

Mechanical strength with UV resistance, oxygen/nutrient permeability, protective barrier, transparency.

How can hydrogels of collagen I and phosphorylcholine benefit corneal TE?

Provide mechanical stability and resistance to enzymatic or UV degradation while maintaining transparency.

Which approach can improve epithelial coverage on corneal implants?

Coating with ECM proteins/adhesive peptides or covalently binding growth factors to enhance cell adhesion and migration.

Why might inducing apoptosis of myofibroblasts improve corneal transparency?

Myofibroblasts deposit opaque scar tissue; their removal reduces haze and restores clarity.

Which fetal ECM components are proposed for pro-regenerative biomaterials?

Hyaluronan, chondroitin sulfate, tenascin, fibronectin, and collagen III.

What is a potential drawback of using fetal cells for adult wound therapy?

Immunogenicity leading to rejection.

Define anoikis in the context of wound healing.

Apoptosis triggered when cells lose proper anchorage to the extracellular matrix.

Which intracellular pathways connect integrin signalling to cell survival?

Rac/JNK pathway and MAPK pathway.

How does CTGF contribute to scarring?

Promotes excessive ECM deposition leading to fibrosis.

What technique is commonly used in vitro to study cell migration resembling wound closure?

'Scratch' or 'wound healing' assay.

Which integrin subunit is implicated in blood vessel formation during healing?

β1 integrin.

Name two common clinical skin grafting techniques.

Full-thickness skin grafts (FTG) and Split-thickness skin grafts (SSG).

What is the Meek technique used for?

Expanding full-thickness skin grafts to cover larger wound areas.

Which growth factor combination pattern (high vs. low) distinguishes adult from fetal wound healing?

Adult: high TGF-β1/β2, low TGF-β3; Fetal: low TGF-β1/β2, high TGF-β3.

State one proposed future avenue for regenerative wound therapy mentioned in the wrap-up slides.

Delivery of pro-regenerative molecules, inhibition of scarring pathways, or smart biomaterials mimicking fetal ECM.