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title: "Fibroblast | PepTracker Pro"
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[Glossary](/glossary)/ Fibroblast 

Research 

# Fibroblast

## Definition

A cell type that produces collagen and other components of the extracellular matrix, essential for tissue repair.

## Why It Matters

Many tissue-repair peptides exert their effects by stimulating fibroblast activity.

## Related Terms

[Collagen](/glossary/collagen)[Extracellular Matrix](/glossary/extracellular-matrix)

## Related Peptides

[BPC-157 

A pentadecapeptide derived from human gastric juice, studied for tissue repair and gut-protective properties.

](/peptides/bpc-157)[BPC/TB500 Blend 

A combined formulation of BPC-157 and TB-500, the two most commonly paired tissue repair peptides.

](/peptides/bpc-tb500-blend)[Difelikefalin 

Difelikefalin (Korsuva in the U.S., Kapruvia in Europe) is a synthetic tetrapeptide built entirely from D-amino acids - D-Phe-D-Phe-D-Leu-D-Lys capped with a 4-aminopiperidine-4-carboxylic acid - that acts as a selective agonist at the kappa opioid receptor. Its defining property is what it cannot do: the molecule is hydrophilic and bulky enough that it does not meaningfully cross the blood-brain barrier, so it reaches kappa receptors on peripheral sensory nerve endings, keratinocytes and immune cells while leaving the central kappa receptors that produce dysphoria and hallucinations largely untouched. It has no activity at the mu opioid receptor, so it carries neither euphoria nor respiratory depression. In the Phase 3 KALM-1 and KALM-2 trials in hemodialysis patients with moderate-to-severe chronic-kidney-disease-associated pruritus, roughly 40-51% of difelikefalin-treated patients achieved a clinically meaningful (>=3-point) reduction on the 10-point Worst Itching Intensity NRS at 12 weeks versus roughly 20-28% on placebo. The FDA approved intravenous difelikefalin in August 2021; the EU approved it as Kapruvia in April 2022.

](/peptides/difelikefalin)[FOXO4-DRI 

A senolytic peptide designed to selectively clear senescent cells by disrupting FOXO4-p53 interaction.

](/peptides/foxo4-dri)

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