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CURRENT CONCEPTS

Growth Factors (GF) and Where are they?

Platelet Rich Plasma (PRP) In plasma they are mainly produced by the platelets and
stored in the α – granules within platelets. Their amount

All PRP Are Not Alike
is correlated with the number of platelets. They are also
synthesized by some tissues such as liver or fat tissue. Some

similar proteins can be found outside the plasma in pituitary,
kidneys, submandibular gland, lacrimal gland and Brunner
gland.
Ramon Cugat, MD, PhD

Fundacín Garcia Cugat
How do they act?
Mutualidad de Futbolistas Espãoles–
They are released from the cell that produces them or from
Federacín Espãola de F́tbol their storage granules under thrombine action first then a
Hospital Quiŕn Barcelona, SPAIN
cascade is initiated. They interact with a corresponding cell

membrane receptor. They act as signals sent between cells
to complete a specific activity extracellular or intracellular

Additional Author:
amplifying the signal.

Francois Kelberine, MD
It is of great interest that the same package of GF acts
Clinique Provencale Parc Rambot Aix en Provence, France
differently depending on the cellular environment: target

tissue (muscle, tendon, cartilage,.) and timeframe of the
healing process.
Introduction

Greater understanding of the cell structure and function have What are they called and what do they do?
opened new fields of investigation for possible health benefits The names of the growth factors indicate their activity and/or

of living beings.
origin. Here are some examples:
• PDGF(PlateletDerivedGF)ischemotacticforfibroblasts,
To act, living cells must find a support or three-dimensional
matrix and should receive stimuli from signaling molecules smooth muscle cells and leucocytes (3). It stimulates
neutrophil phagocytosis, leads to the release of proteins
and growth factors.
from neutrophils and monocytes. It initiates collagen
This has led to a new specialty, Regenerative Medicine, synthesis and connective tissue replication.
which according to authors such as Greenwood (1) Anitua
and Sanchez (2) among many others is an emerging field of • VEGF(VascularEndothelialGF)stimulatesangiogenesisby
endothelial cells replication.
interdisciplinary research and clinical applications focused
on the repair, replacement or regeneration of cells, tissues • TGF-β1(TransformingGF)belongstothefamilyofBMP
(Bone Morphogenetic Proteins) among many others (4). Its
or organs to restore impaired function from any cause,
including congenital defects, disease and trauma. It uses a action is cell-dependant in relation with the environment. It
limits (regulates) cell proliferation. It increases extracellular
combination of technological approaches that go beyond
traditional transplantation and replacement therapies. These matrix synthesis and inhibits its degradation. And it has an
immunosuppressive effect (5).
approaches may include, but are not limited to, the use of
stem cells, progenitor cells, soluble molecules, recombinant • EGF(Epidermalgrowthfactor)attractsfibroblastand
stimulates its mitosis as well as keratinocyte, increases
GF, biomaterials, nanotechnology, genetic engineering, tissue
engineering and advanced cell therapy.
fibronectin and collagen synthesis. So it accelerates
wound closure.
This article focusses on PRP and GF: what they are, how
they are obtained, how they work and what benefits they can • FGFa&b(acidandbasicFibroblasticGF)stimulates
proliferation of most cells involved in repair, is produced
bring to the field of Orthopedic Surgery.
by numerous types of cells so their amount is not only
What are Growth Factors (GF)?
correlated to the number of platelets.

They are proteins, key mediators that regulate activities • IGF(InsulinlikeGF)typeIorII,HGF(HepatocyteGF).
especially hæmostasis and tissue repair. They are involved in They are not synthesized by platelets so they are not
correlated to their amount. They induce cell proliferation,
almost all physiological healing processes. Some authors call
them proteins, Differentiation Factors and Growth Factors.
differentiation and synthesis of type I collagen.

Many experimental, animal and clinical studies support
that GFs promote hemostasis, cell proliferation, migration

(chemotaxis) and differentiation. So they lead to angiogenesis,
regeneration and extracellular matrix synthesis especially in

acute injuries.

ISAKOS NEWSLETTER 2014: Volume II 29