Growth factors, receptors involved in tissue repair regeneration and w

Growth factors, receptors involved in tissue repair regeneration and woung healing md pathology exam question robbins based answer

Reading File

Finding Sources

Searching PubMed

wound healing AND growth factors

Searching the Web

Robbins pathology tissue repair regeneration growth factors receptors wound healing

Reading File

Finding Sources

Reading File

Reading Web Page

https://www.ncbi.nlm.nih.gov/books/NBK534261

Growth factors and receptors in tissue repair, regeneration and wound healing

Introduction

Growth factors are polypeptides that bind specific cell-surface receptors and activate signals promoting cell survival, proliferation, migration, differentiation, and synthesis of extracellular matrix (ECM). They are essential for regeneration of injured tissue, angiogenesis, granulation-tissue formation, re-epithelialization, collagen deposition, and scar remodeling.

The most important source in an injured tissue is the activated macrophage. Platelets, endothelial cells, keratinocytes, fibroblasts, and stromal cells also contribute.
Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 35.

Major growth factors in repair and regeneration

Growth factor	Main sources	Receptor / signaling	Major role in repair
EGF	Activated macrophages, keratinocytes, salivary glands, many cells	EGFR (ERBB1), receptor tyrosine kinase	Mitogenic for epithelial cells and fibroblasts; promotes epithelial migration and granulation tissue formation
TGF-alpha	Macrophages, keratinocytes, epithelial cells	EGFR, receptor tyrosine kinase	Proliferation of hepatocytes and other epithelial cells; contributes to epithelial regeneration
HGF (scatter factor)	Fibroblasts, liver stromal cells, endothelial cells	c-MET, receptor tyrosine kinase	Proliferation of hepatocytes and epithelial cells; increased cell motility. Important in liver regeneration
VEGF	Mesenchymal cells, macrophages, keratinocytes and other wound cells	VEGFR-1, VEGFR-2, receptor tyrosine kinases	Principal mediator of angiogenesis; endothelial proliferation and migration; increased vascular permeability
PDGF	Platelets, macrophages, endothelial cells, smooth muscle cells, keratinocytes	PDGFR-alpha/beta, receptor tyrosine kinase	Chemotaxis and proliferation of fibroblasts, macrophages, smooth muscle cells and endothelial cells; promotes ECM synthesis and vessel stabilization
FGF-2 (basic FGF)	Macrophages, mast cells, fibroblasts and other mesenchymal cells	FGFR, receptor tyrosine kinase, aided by heparan sulfate	Fibroblast proliferation, angiogenesis, migration of cells into wound; ECM deposition
TGF-beta	Platelets, macrophages, lymphocytes, endothelial cells, fibroblasts	TGF-beta receptors I and II, serine/threonine kinase receptors, via SMAD proteins	Most important fibrogenic cytokine: fibroblast chemotaxis and proliferation, collagen/fibronectin/proteoglycan synthesis, reduced ECM degradation, myofibroblast formation
IGF-1	Macrophages, fibroblasts, platelets and liver	IGF-1 receptor, receptor tyrosine kinase	Cell proliferation, protein synthesis and matrix formation
KGF / FGF-7	Fibroblasts	FGFR on keratinocytes	Keratinocyte proliferation and re-epithelialization

Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 35.

Receptors and their significance

1. Receptor tyrosine kinases

These include receptors for EGF, TGF-alpha, HGF, VEGF, PDGF, FGF, and IGF-1.

Ligand binding causes receptor dimerization and autophosphorylation.
Downstream pathways include RAS-MAPK, PI3K-AKT, and related signaling cascades.
Effects: cell-cycle entry, DNA synthesis, survival, migration, and protein synthesis.

Examples:

EGF/TGF-alpha → EGFR
HGF → c-MET
PDGF → PDGFR
VEGF → VEGFR
FGF → FGFR

2. Serine/threonine kinase receptors

TGF-beta binds TGF-beta receptor type II, which recruits and activates type I receptor. The receptor complex phosphorylates SMAD2/3, which complex with SMAD4 and enter the nucleus to regulate transcription.

Main consequences:

Increased collagen, fibronectin and proteoglycan production
Decreased matrix degradation by reducing metalloproteinase activity and increasing TIMPs
Fibroblast activation and conversion to myofibroblasts
Wound contraction and fibrosis

Role in phases of wound healing

1. Hemostasis and inflammation

Platelets release PDGF, TGF-beta, VEGF, EGF, IGF-1 and FGF.
PDGF recruits neutrophils, macrophages and fibroblasts.
Macrophages subsequently become the major source of growth factors.

2. Proliferative phase: granulation tissue formation

VEGF and FGF-2 cause angiogenesis.
PDGF recruits fibroblasts and stimulates their proliferation.
TGF-beta promotes ECM and collagen synthesis.
New capillaries plus proliferating fibroblasts form granulation tissue.

3. Re-epithelialization

EGF, TGF-alpha, FGF and KGF stimulate keratinocyte migration and proliferation.
Epithelial cells migrate from wound margins and adnexal structures to cover the defect.

4. Wound contraction and remodeling

TGF-beta promotes fibroblast to myofibroblast differentiation.
Myofibroblasts contract the wound.
TGF-beta favors collagen deposition and reduced degradation, therefore excess or persistent signaling can produce fibrosis, hypertrophic scars, and keloids.

Role in regeneration

Regeneration occurs through proliferation of surviving mature cells and, when needed, tissue stem cells. Growth factors act together with signals from the ECM, especially through integrins.

Liver regeneration

The liver is the classic example:

IL-6 from Kupffer cells primes hepatocytes to respond.
HGF and TGF-alpha stimulate proliferation of residual hepatocytes.
When hepatocyte replication is impaired, hepatic progenitor cells in the canals of Hering contribute to regeneration.

Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 110.

High-yield conclusion

PDGF: chemotaxis, fibroblasts, ECM, vessel maturation.
VEGF: angiogenesis and vascular permeability.
FGF: fibroblast proliferation and angiogenesis.
EGF/TGF-alpha/KGF: epithelial and keratinocyte proliferation, re-epithelialization.
HGF: hepatocyte and epithelial regeneration, cell motility.
TGF-beta: key mediator of fibrosis, collagen deposition, wound contraction and reduced ECM degradation.

A recent systematic review of topical growth-factor therapy concerns clinical diabetic-wound treatment rather than altering these core Robbins mechanisms (PMID: 38477463).

One page revision pdf

Reading File

Browsing Directory

Running Command

mkdir -p "/tmp/workspace/wound-healing-revision/src" "/tmp/workspace/wound-healing-revision/output" && python - <<'PY' from reportlab.lib.pagesizes import A4 from reportlab.lib import colors from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle from reportlab.lib.enums import TA_CENTER, TA_LEFT from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle, KeepTogether from reportlab.lib.units import cm from reportlab.pdfbase.pdfmetrics import stringWidth from pypdf import PdfReader out='/tmp/workspace/wound-healing-revision/output/Growth_Factors_Wound_Healing_One_Page_Revision.pdf' PAGE_W, PAGE_H = A4 margin=0.72*cm doc=SimpleDocTemplate(out,pagesize=A4,rightMargin=margin,leftMargin=margin,topMargin=0.57*cm,bottomMargin=0.55*cm) styles=getSampleStyleSheet() styles.add(ParagraphStyle(name='TitleX',parent=styles['Title'],fontName='Helvetica-Bold',fontSize=15.3,leading=17.2,alignment=TA_CENTER,textColor=colors.HexColor('#12365A'),spaceAfter=2)) styles.add(ParagraphStyle(name='SubX',parent=styles['Normal'],fontName='Helvetica',fontSize=7.6,leading=8.7,alignment=TA_CENTER,textColor=colors.HexColor('#4B5563'),spaceAfter=5)) styles.add(ParagraphStyle(name='H',parent=styles['Heading2'],fontName='Helvetica-Bold',fontSize=8.5,leading=9.6,textColor=colors.white,spaceBefore=3,spaceAfter=2)) styles.add(ParagraphStyle(name='B',parent=styles['BodyText'],fontName='Helvetica',fontSize=7.0,leading=8.15,spaceAfter=1.2)) styles.add(ParagraphStyle(name='Small',parent=styles['BodyText'],fontName='Helvetica',fontSize=6.55,leading=7.55,spaceAfter=0.7)) styles.add(ParagraphStyle(name='Cell',parent=styles['BodyText'],fontName='Helvetica',fontSize=6.15,leading=7.0)) styles.add(ParagraphStyle(name='CellB',parent=styles['BodyText'],fontName='Helvetica-Bold',fontSize=6.15,leading=7.0)) def P(x, style='B'): return Paragraph(x,styles[style]) def bar(text): t=Table([[P(text,'H')]],colWidths=[19.55*cm]) t.setStyle(TableStyle([('BACKGROUND',(0,0),(-1,-1),colors.HexColor('#1E5A88')),('LEFTPADDING',(0,0),(-1,-1),5),('RIGHTPADDING',(0,0),(-1,-1),4),('TOPPADDING',(0,0),(-1,-1),2),('BOTTOMPADDING',(0,0),(-1,-1),2)])) return t story=[] story += [P('GROWTH FACTORS, RECEPTORS & WOUND HEALING','TitleX'),P('Robbins-based pathology revision sheet | Tissue repair and regeneration','SubX')] story += [bar('CORE PRINCIPLE')] story += [P('Growth factors are polypeptides that bind specific cell-surface receptors and drive survival, cell-cycle entry, proliferation, migration, differentiation and ECM synthesis. In injured tissue, activated macrophages are the major source; platelets, keratinocytes, fibroblasts, endothelial and stromal cells also contribute. Signals from integrins binding ECM cooperate with growth-factor signals.')] story += [bar('HIGH-YIELD GROWTH FACTORS')] data=[[P('Factor','CellB'),P('Main source(s)','CellB'),P('Receptor / key effect in repair','CellB')], [P('EGF','CellB'),P('Macrophages, keratinocytes, salivary glands','Cell'),P('EGFR (ERBB1), RTK: epithelial migration and proliferation; granulation tissue','Cell')], [P('TGF-alpha','CellB'),P('Macrophages, keratinocytes, epithelial cells','Cell'),P('EGFR, RTK: hepatocyte and epithelial-cell proliferation','Cell')], [P('HGF (scatter factor)','CellB'),P('Fibroblasts, liver stromal cells, endothelium','Cell'),P('c-MET, RTK: hepatocyte/epithelial proliferation and motility; liver regeneration','Cell')], [P('VEGF','CellB'),P('Mesenchymal and wound cells','Cell'),P('VEGFR-1/2, RTKs: endothelial proliferation, migration, permeability, angiogenesis; induced by hypoxia via HIF-1','Cell')], [P('PDGF','CellB'),P('Platelets, macrophages, endothelium, SMCs, keratinocytes','Cell'),P('PDGFR-alpha/beta, RTKs: chemotaxis and proliferation of fibroblasts, macrophages, SMCs, endothelium; ECM synthesis; vessel maturation','Cell')], [P('FGF-2 (basic FGF)','CellB'),P('Macrophages, mast cells, fibroblasts','Cell'),P('FGFR, RTK: fibroblast proliferation, angiogenesis and migration into wound','Cell')], [P('TGF-beta','CellB'),P('Platelets, macrophages, lymphocytes, endothelium, fibroblasts','Cell'),P('TGF-beta R-I/R-II, serine/threonine kinase → SMAD: key fibrogenic factor, ECM/collagen synthesis, myofibroblasts, contraction, reduced ECM degradation','Cell')], [P('KGF (FGF-7)','CellB'),P('Fibroblasts','Cell'),P('FGFR on keratinocytes: re-epithelialization','Cell')], ] t=Table(data,colWidths=[2.55*cm,4.1*cm,12.9*cm],repeatRows=1) t.setStyle(TableStyle([('BACKGROUND',(0,0),(-1,0),colors.HexColor('#DCEAF5')),('TEXTCOLOR',(0,0),(-1,0),colors.HexColor('#12365A')),('GRID',(0,0),(-1,-1),0.25,colors.HexColor('#AABCCB')),('VALIGN',(0,0),(-1,-1),'TOP'),('LEFTPADDING',(0,0),(-1,-1),3),('RIGHTPADDING',(0,0),(-1,-1),3),('TOPPADDING',(0,0),(-1,-1),2),('BOTTOMPADDING',(0,0),(-1,-1),2),('ROWBACKGROUNDS',(0,1),(-1,-1),[colors.white,colors.HexColor('#F7FAFC')])])) story += [t] story += [bar('PHASE-WISE MAP OF WOUND HEALING')] phase=[[P('Phase','CellB'),P('Dominant factors and outcome','CellB')], [P('1. Hemostasis + inflammation','CellB'),P('Platelets release PDGF, TGF-beta, VEGF, EGF, IGF-1 and FGF. PDGF recruits inflammatory cells; macrophages then become the main growth-factor source.','Cell')], [P('2. Proliferation / granulation tissue','CellB'),P('VEGF + FGF-2: angiogenesis. PDGF: fibroblast recruitment/proliferation. TGF-beta: collagen and other ECM deposition.','Cell')], [P('3. Re-epithelialization','CellB'),P('EGF, TGF-alpha, FGF, KGF: keratinocyte migration and proliferation from wound margins/adnexa.','Cell')], [P('4. Contraction + remodeling','CellB'),P('TGF-beta drives myofibroblast differentiation and contraction. Persistent excess TGF-beta promotes fibrosis, hypertrophic scar and keloid.','Cell')], ] t2=Table(phase,colWidths=[4.3*cm,15.25*cm],repeatRows=1) t2.setStyle(TableStyle([('BACKGROUND',(0,0),(-1,0),colors.HexColor('#DCEAF5')),('GRID',(0,0),(-1,-1),0.25,colors.HexColor('#AABCCB')),('VALIGN',(0,0),(-1,-1),'TOP'),('LEFTPADDING',(0,0),(-1,-1),3),('RIGHTPADDING',(0,0),(-1,-1),3),('TOPPADDING',(0,0),(-1,-1),2),('BOTTOMPADDING',(0,0),(-1,-1),2),('ROWBACKGROUNDS',(0,1),(-1,-1),[colors.white,colors.HexColor('#F7FAFC')])])) story += [t2] story += [bar('EXAM FINISHER: REGENERATION + ONE-LINE RECALL')] story += [P('Liver regeneration: Kupffer-cell IL-6 primes hepatocytes; HGF and TGF-alpha stimulate residual hepatocyte proliferation. If hepatocyte replication is impaired, progenitor/stem cells contribute. Mnemonic: “P-V-F-E-T” = PDGF pulls fibroblasts, VEGF makes vessels, FGF builds granulation, EGF covers epithelium, TGF-beta lays collagen and contracts scar.')] story += [Spacer(1,2),P('Source: Robbins, Cotran & Kumar, Pathologic Basis of Disease: “Growth Factors and Receptors” and “Repair by Regeneration, Healing and Fibrosis.”','Small')] doc.build(story) r=PdfReader(out) assert len(r.pages)==1, f'Expected 1 page, got {len(r.pages)}' print(out) print('Pages:',len(r.pages),'size:',__import__('os').path.getsize(out)) PY

Growth Factors Wound Healing One Page Revision

PDF Document · PDF

This is a shared conversation. Sign in to Orris to start your own chat.