Full text of DOI:10.1097/00005537-200205000-00020

The Laryngoscope
Lippincott Williams & Wilkins, Inc., Philadelphia
© 2002 The American Laryngological,
Rhinological and Otological Society, Inc.
Basic Fibroblast Growth Factor in Human
Saliva Decreases With Aging
Anders Westermark, DDS, PhD; Ilmari Pyykko¨, MD, PhD; Mikael Magnusson, DDS;
Hisayoshi Ishizaki, MD, PhD; Pirkko Ja¨ntti, MD, PhD; Gysbert van Setten, MD, PhD
Objective: Basic fibroblast growth factor (bFGF)
has significant properties in wound healing and tis-
sue repair and is suggested to be of importance for the
maintenance of mucosal integrity in the upper diges-
tive tract. The purpose of the present study was to
identify any age-dependent variations in the concen-
tration of bFGF in human saliva. Study Design: Non-
prospective, cross-sectional pilot study. Methods: The
study was based on findings from 182 healthy volun-
teers with ages ranging from 4 to 97 years. Mixed
saliva samples were obtained by drooling. The saliva
concentration of bFGF was determined with a com-
mercially available enzyme-linked immunosorbent
assay kit. Results: The mean saliva concentration of
bFGF was 0.41 pg/mL with no gender differences. In
persons aged 4 to19 years, the mean concentration
was 0.72 pg/mL; in those aged 20 to 65 years, 0.33
pg/mL; and in those aged 66 to 97 years, 0.005 pg/mL.
These age-dependent differences were highly signifi-
cant. In the youngest group the saliva concentration
of bFGF varied more than in the other groups. Con-
clusions: The saliva concentration of bFGF varies
with individual age, with the highest levels among
young individuals, even levels during a mature phase
of life, and low levels toward the end of the life cycle.
This strongly suggests a physiological implication of
bFGF in saliva. Key Words: Growth factor, saliva, age.
Laryngoscope, 112:887–889, 2002
corpus luteum, and placenta. In previous studies we have
demonstrated the presence of bFGF in tear fluids and in
saliva.2–4
The bFGF has been demonstrated to stimulate pro-
liferation of cells of mesodermal and neuroectodermal or-
igin. Presence of bFGF accelerates proliferation of endo-
thelial cells and fibroblasts; consequently, bFGF is
considered to be highly important in wound healing and
tissue repair.5 The bFGF stimulates the proliferation of
gastrointestinal tract epithelium, which has been shown
to accelerate the healing of experimental intestinal ulcers
in rats,9 and it has been suggested that bFGF in the saliva
may be partly responsible for maintenance of mucosal
health in the entire upper digestive tract.
In a previous study, we demonstrated that saliva
concentration of bFGF was higher among smokers than
among nonsmokers, but also that there was no age-related
differences in saliva concentration of bFGF among indi-
viduals aged 22 to 49 years.4 In the current study, we
evaluated saliva concentration of bFGF in a larger popu-
lation of healthy nonsmoking individuals covering an age
span from young children to a geriatric population.
MATERIAL AND METHODS
Saliva samples were obtained from 185 healthy volunteers
after informed consent according to the Declaration of Helsinki.
Samples from the youngest children were obtained in a kinder-
garten after informed consent from their parents. Samples from
the geriatric part of the population were collected in a long-term
care facility for elderly individuals.
INTRODUCTION
Fibroblast growth factor basic or basic fibroblast
growth factor (bFGF), also called fibroblast growth
factor-2, belongs to a growth factor family that currently
consists of nine members, and is on of the most extensively
studied in its family.1 It has been isolated from a variety
of sources, such as neural tissue, pituitary, adrenal cortex,
The saliva was nonstimulated and was collected by drooling
or spitting into a mug, from which specimen approximately 1.5
mL of saliva was collected in a test tube; the test tube was sealed
immediately and thereafter stored at Ϫ80°C until the day of
analysis. Information was registered about gender and age of the
tested individuals.
At the day of analysis the samples were thawed at room
temperature. Then the samples were centrifuged at 14,000 rpm
for 8 minutes. Thereafter, the water phase of the saliva was
separated for the assay procedure. The samples were analyzed
with a commercially available enzyme-linked immunosorbent as-
say (ELISA) kit (R&D System, Minneapolis, MN) and the instruc-
tion manual provided by the company was followed, as in our
previous studies.3,4 The system uses antibodies specific for fibro-
blast growth factor bound to wells in microtiter plates. A 2-hour
incubation with the saliva samples was followed by repeated
From the Departments of Maxillofacial Surgery (A.W., M.M.) and
Otolaryngology (I.P.), Karolinska Hospital, Stockholm, Sweden; the De-
partment of Otolaryngology, Kikugawa Hospital (H.I.), Shijuoka, Japan;
the Department of Otolaryngology, Health Center Hospital of Oulu (P.J.),
Oulu, Finland; and the Department of Ophthalmology (G.V.S.), St. Erik Eye
Hospital, Stockholm, Sweden.
Editor’s Note: This Manuscript was accepted for publication Decem-
ber 18, 2001.
Send Correspondence to Anders Westermark, DDS, PhD, Depart-
ment of Maxillofacial Surgery, Karolinska Hospital, SE 171 76 Stockholm,
Sweden. E-mail: anders.westermark@ks.se
Laryngoscope 112: May 2002
Westermark et al.: Basic Fibroblast Growth Factor
887

washings. Thereafter, an enzyme-linked polyclonal bFGF-specific
antibody was added to the wells. A substrate solution was added,
followed by incubation for 1 hour. An amplifier solution was
added before the reaction was stopped with 2N sulfuric acid.
Optical densities of the wells were determined with a spectropho-
tometer at 490 nm with a correction wavelength of 690 nm. A
standard curve was obtained according to the values of a stan-
dard dilution of recombinant human bFGF dilutions ranging from
0.0 to 36 pg/mL, in duplicate determination. The statistical eval-
uation was performed with unpaired Student t test, and the level
of significance was set at P levels below .05.
RESULTS
Of the 185 samples, 182 were included in the study,
representing 69 male and 113 female individuals with
ages ranging from 4 to 97 years. The distribution of bFGF
in saliva is illustrated in Table I and in Figures 1 and 2.
The mean saliva concentration of bFGF was 0.41 pg/mL.
There was no significant difference between male and
female individuals. Among male individuals the mean
concentration was 0.46 pg/mL, and among female individ-
uals, 0.38 pg/mL. Young individuals (aged 4–19 y) had a
mean concentration of 0.72 pg/mL; individuals aged 20 to
65 years, 0.33 pg/mL; and those aged 66 to 97 years, 0.005
pg/mL (Table I). These age-related differences were highly
significant, with P levels below .01 both between the
young group and the middle group and between the mid-
dle group and the old group. There was a large variation in
saliva concentration of bFGF among the young individuals
(Table I; Figs. 1 and 2). Three elderly individuals pos-
sessed high levels (4.23, 3.53, and 2.59 pg/mL), but they
were excluded from the study because of the presence of
intraoral pathological processes.
Fig. 1. Diagram of the distribution of basic fibroblast growth factor
in saliva (picograms per milliliter saliva). Age ϭ years.
little bFGF seems to be normally produced, unless signif-
icant disease is present.
Interesting was the wide variation observed in the
saliva concentration of bFGF in the young individuals.
However, there may be an obvious explanation for that,
emphasizing the physiological importance of bFGF in sa-
liva. Growth factors stimulate target cells to chemotaxis
and mitosis.5 One of these factors is bFGF, which is re-
leased partly in wounded tissues.6 Intraoral wounds such
as teething are present during a relatively long age-
period, from approximately 2.5 to 13 or 14 years. During
this time, there are frequent periods with tooth eruption
or tooth exchange. Thereafter, there is a relatively wide
period of the upper teens when the wisdom teeth start to
erupt. Such conditions represent rapidly healing wounds
and therefore may be involved in the high and varying
saliva concentrations of bFGF among the young individu-
als. However, no clinical records were taken for the young
individuals examined.
Another cause of high salivary concentration of bFGF
may be smoking habits.4 Many of the children aged 12 to
15 were examined in connection with a visit at an orth-
odontist’s evaluation for possible orthodontic treatment.
At that occasion, most of the patients were accompanied
by one parent or both, and it seems unlikely that any
smoking would have been confessed under those circum-
stances. In our previous study on bFGF in human saliva,
we observed significantly higher saliva concentrations of
bFGF among smokers than among nonsmokers.4 How-
ever, those differences were not, by far, of the magnitude
that we observed in the group of young individuals in the
present study. Therefore, we think that the high concen-
trations of salivary bFGF in the two youngest decades in
the current study represent a true age-dependent phe-
nomenon, just as the low concentrations in the older and
DISCUSSION
The present study repeated our previous finding that
there seems to be an even distribution of saliva concen-
tration of bFGF among individuals in the third, fourth,
and fifth decades of life. A new finding was that there were
significantly higher bFGF concentrations in younger indi-
viduals, but also with large variations in bFGF concentra-
tions. Moreover, there were low concentrations of bFGF in
the saliva of the older individuals and the geriatric popu-
lation. Because bFGF is considered to be one of the most
potent growth factors for fibroblast and endothelial cell
proliferation, it seems natural that growing individuals
with intense proliferative activity of intraoral tissues pos-
sess the highest amounts of bFGF in their saliva. During
the more mature part of the life cycle with well-balanced
regulation of cell proliferation, bFGF levels seem to be
relatively stable, and toward the end of the life cycle very
TABLE I.
Distribution of bFGF in Saliva in Individuals Aged 4 to 97 Years.
Age Group
Mean
(pg/mL)
Median
(pg/mL)
Range
(pg/mL)
Years
Number
4–19
55
101
26
0.72
0.33
0.005
0.55
0.27
0.00
0.01–2.58
0.00–0.90
0.00–0.94
20–65
66–97
Laryngoscope 112: May 2002
888
Westermark et al.: Basic Fibroblast Growth Factor

gressed and disappeared and, simultaneously, the urinary
bFGF fell to normal levels. However, no evaluation of
salivary bFGF was mentioned by Kaban et al.12
Today, we still lack much information on growth fac-
tors in human saliva. Further studies should include not
only mixed saliva but also gland-specific saliva and should
be directed to study a vast array of growth factors in the
saliva. Growth factor responses to aging, radiation treat-
ment, and the abuse of tobacco and alcohol might give
indications about the roles of growth factors in health and
disease. However, the interactions between various
growth factors are poorly understood, and the interactions
between growth factors and upregulation or downregula-
tion of their receptors appear to make the impression of
the system even more complex.
CONCLUSION
The saliva concentration of bFGF seems to be age
dependent with high levels during childhood and youth,
even levels during the mature period of life, and low levels
during the last decades of life. These differences may be
linked to age-dependent mucosal degeneration in the up-
per digestive tract.
Fig. 2. Basic fibroblast growth factor in saliva (picograms per
milliliter saliva) in the following age groups: Group 1 ϭ 4 to 19 y;
group 2 ϭ 20 to 65 years; and group 3 ϭ 66 years and older.
Gender: 1 ϭ male individual; 2 ϭ female individual.
geriatric population do. It is interesting, but not surpris-
ing, that serum levels of insulin growth factor-I vary with
age in a somewhat similar pattern with a peak around the
period of maximal growth during youth and, thereafter, a
slow reduction over the mature and aging periods of the
life cycle.7 It was also demonstrated previously that with
increasing age there is a decline in gastrointestinal ab-
sorption of growth factors in the rat.8 Just as growth
factors are most active during growth, a physiological
downregulation of their presence toward the end of the life
cycle may be assumed. Obviously, however, because three
individuals with oral pathological conditions demon-
strated high levels, the potential to produce bFGF re-
mains, despite aging. Such association between bFGF and
pathological processes has been previously described.1
Experimentally, bFGF in saliva has been described to
heal duodenal ulcers in rodents,9 and similar findings in
humans have been reported with epidermal growth fac-
tor.10 Therefore, it has been suggested that growth factors
in saliva may be responsible for the maintenance of mu-
cosal integrity in the entire upper digestive tract. In their
report, Sabbadini and Berczi11 speculated that the sub-
mandibular gland may be a key organ in the neuroimmu-
noregulatory network. They reported that in rodents the
submandibular gland is fully integrated into the neuroen-
docrine system.11
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conditions. Kaban et al.12 reported on a case of giant cell
tumor of the mandible in which the patient possessed
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