J. Biomedical Science and Engineering, 2011, 4, 200-206 JBiSE
doi:10.4236 /jbi se. 2011.430 28 Published Online March 2011 (http://www.SciRP.org/journal/jbise/).
Published Online March 2011 in SciRes. http://www.scirp.org/journal/JBiSE
Cationic polypeptides in a concept of oppositely charged po-
lypeptides as prevention of postsurgical intraabdominal adhe-
sions
Karolin Isaksson, Daniel Åkerberg, Katarzyna Said, Bob by Tingstedt
Department of Surgery, University Hospital of Lund, Sweden.
Received 29 November 2010; revised 3 January 2011; accepted 5 January 2011.
ABSTRACT
Background: Two differently charged polypeptides,
α-poly-L-lysine and poly-L-glutamate, have previ-
ously been shown to effectively reduce postoperative
intraa bdominal adhesions. Though α-poly-L-lysine
showed toxicity in doses too close to the lowest the-
rapeutic dose, the aim in the present study was to
investigate the possible antiadhesive effect of another
four cationic polypeptides. Ma te ria ls/Me tho d s: 125
mice were studied with a standardized and repro-
ducible adhesion model and given epsilon poly-L-
lysine, lact oferrin, lysozyme and polyarginine respec-
tively in a combination with poly-L-glutamate. Epsi-
lon poly-L-lysine was also tested in different concen-
trations and as single treatment. Results: All four
cationic polypeptides above showed a significantly
better a nt i-adhesive effect than the controls receiving
saline (p < 0.05). Epsilon poly-L-lysine had the best
antiadhesive effect of the new substances tested in the
experi ment. Si ngle treat ment w it h the epsilon po ly -L-
lysine showed toxic side effects. Discussion: We have
shown that epsilon poly-L-lysine, polyarginine, ly-
sozyme and lactoferrin, in descending order, all can
reduce postoperative intraabdominal adhesions in
mice when combined with poly-L-glutamate. There
were side effects of epsilon poly-L-lysine resembling
those of α-poly -L-lysine, alt houg h less to xic. The a nti-
adhesive effect of epsilon poly-L-lysine did not reach
the level of α-poly -L-lysine. Further studies will con-
centrate on additional investigation, trying to modify
the α-poly-L-lysine to low er its toxicity. The less toxic
epsilon poly-L-lysine also needs further attention in
our research of antiadhesive bioactive polypeptides.
Keywords: Postoperative Adhesions; Bioactive
Polypeptides; Molecular Structure
1. INTRODUCTION
Postoperative abdominal adhesion formation is a sig-
nificant clinical problem worldwide, especially follow-
ing lower abdominal surgery [1,2]. Adhesions contain
fibrotic tissue that can create bridges between bowels,
organs and the abdominal wall, thus creating intraab-
dominal problems. Abdominal adhesions are not only the
leading cause of small bowel obstruction, a common
diagnosis often demanding surgical treatment, but also
cause abdominal pain and female infertility [3].
The pathogenesis is not completely elucidated but the
overall picture is quite clear [4]. The peritoneal surface
is very delicate and susceptible to damage. In the process
of adhesion formation, the plasmin system plays a cru-
cial part with an imbalance between fibrin formation and
degradation at the injured peritoneal site [5-6]. Important
factors involved in degradation and formation of local
peritoneal adhesions are tPA and PAI-1 [7-10].
The annual cost of adhesion-related diagnosis in
Sweden has been estimated at about 6.3 million €/mil-
lion inhabitants [11].
Various products are available on the market and are
used to prevent/reduce the amount of postoperative ad-
hesions [12, for example hyaluronic acid [13] and its
derivates and soluble polysaccharides [14] and phos-
pholipids [15]. However, these formulas have not been
shown to reduce the risk of small bowel obstruction [12].
In previous experimental studies we have shown very
promising results in the reduction of postoperative ab-
dominal adhesions using a combination of differently
charged polypeptides, α-poly-L-lysine and poly-L-glu-
tamate [16-18]. The positively charged poly-L-lysine
binds to the negatively charged damaged peritoneal sur-
face and then attaches the negatively charged poly-L-
glutamate to build a neutral matrix preventing adhesion
formation [19]. In a recent study we questioned this
combination due to the toxicity observed when the ani-

K. Isaksson et al. / J. Biomedical S cience and Engineering 4 (2 011) 200-206
Copyright © 2011 SciR es. JBiSE
201
mals were treated with α-poly-L-lysine alone [20]. The
gap between the possible toxicity level of α-poly-L-ly-
sine and the lowest efficient antiadhesive (in combina-
tion with poly-L-gluta mat e) do se is p rob ably too narrow.
The aim of this study was to evaluate the possible an-
tiadhesive effect of another four cationic polypeptides,
i.e. epsilon poly-L-lysine, lactoferrin, lysozyme and pol-
yarg inine, together with the negatively charged poly-L-
glutamate, based on the concept of using oppositely
charged polypeptides for abdominal adhesion protection.
2. METHOD AND MATERIALS
2.1. An imal s
One hundred and twenty five (125) female NMRI mice
(Scanbur, Stockholm, Sweden) weighing about 25-30
grams were used. The animals were kept in standardized
conditions, at a temperature of 22 degrees Celsius and
with 12 hours of daylight . The animals had free access to
pellets and tap water. The study was conducted with ap-
proval of the local ethical committee and the animals
received human care in compliance with the guidelines
of the Swedish Government and University of Lund,
Sweden.
2.2. Chemicals
Osmotic balanced (2.54 w% glycerol) aqueous solu-
tions of the cationic substances epsilon poly-L-lysine
(4.7 kDa), lactoferrin (80-90 kDa), lysozyme (14.7 kDa),
poly-L-argini ne (15 -70 kDa), α-poly-L-lysi ne (> 30 kDa)
and the anionic poly-L-glutamat (15-50 kDa) were pre-
pared on the day of the experiment and stored in the re-
frigerator until used. The chemicals were all purchased
from Sigma Aldrich (St Louis, Mo., USA) except for
epsilon poly-L-lysine, which was purchased from the
Chisso Corporation (Tokyo, Japan).
2.3. Model
The animals were anaesthesized using an intramuscular
injection of ketamine (Ketalar, Pfizer, N.Y., USA), 150
mg/kg, and xylazaine (Rompun Vet, Bayer AB, Gothen-
burg, Sweden), 7.5 mg/kg. A reproducible and standard-
ized model used in our former experiments was adopted
for thi s study [2 1]. Using an ase ptic technique, a 25 mm
long midline laparotomy was performed after the abdo-
men was shaved and disinfected. Parallel on each side,
about 10 mm from the midline, a 15 mm long incision,
including the peritoneum and underlying mus- cle, was
performed. The lateral incisions were occluded with 4
interrupted sutures each of 5/0 PDS with one suture at
the end of each incision. The midline incision was en-
closed with a running 5/0 PDS in two layers. All the
animals were treated with buprenorphine.
After one week, a time interval chosen to match our
previous studies, the animals were evaluated concerning
intraabdominal adhesions. Anesthesia was induced as
described above. The abdomen was opened through a
U-shaped incision with its base to the right. Adhesions
were considered as tissue (bowels or fat) adherent to the
expe rimental wound o r to anothe r intraab domi nal organ.
The lengths of the incisions as well as the adhesions
covering the wound were measured with a caliper up to
one-te nth o f a milli meter and data were expressed as the
percentage of the wound covered by adhesions. The dis-
tances were measured at the peritoneal level. Other ad-
hesions between intra abdominal organs were also no-
ticed. The animals received sodium pentobarbital straight
after the evaluation for euthanasia, in accordance to the
AVMA Guidelines on Euthanasia, 2 007.
2.4. Experimental Design
2.4.1. First Part
In the first part of the study the animals were randomly
divided into five groups as presented in Table 1 to exam-
ine the antiadhesive effect of different polycations, to-
gether with the polyanion poly-L -glutamate. At the end
of the operation, just before the abdomen was closed, the
treatment substances were installed in volumes and con-
centrations, as shown in the same table. The different
cations were first administered intraabdominally, fol-
lowed by anion poly-L-glutamate within approximately
10 seconds. Groups number five and six were control
groups of 10 animals each, receiving sodium chloride
solution (9 mg/ml) and our previous strong antiadhesive
formula of poly-L-lysine and poly-L-glutamate respect-
tively.
2.4.2. Second Part
In the second part of the study we examined the an-
tiadhesive effect of the cation with the best antiadhesive
proprieties from the first part of the study i.e. epsilon
Table 1. Experimental design, part one. Study of different poly-
peptides.
Grou p Animals
(N) Treatment Concentration (%) Volume ( ml)
1 9 e-PL + PG 0.5 + 0.5 1 + 1
2 10 Lacto + PG 0.5 + 0.5 1 + 1
3 10 Lyso + PG 2.0 + 0.5 1 + 1
4 10 PA + PG 0.5 + 0.5 1 + 1
5 10 NaCl 0.9 2
6 10 αPL + PG 0.5 + 0.5 1 + 1
*e -PL = epsi lon poly-L-lysine, PG = poly-L-glutamate, Lacto = lactoferrin,
Lyso = lysozyme, PA = poly-L-arginine, αPL = alp ha-poly-L-lysine and
NaCl = sodium chloride.

K. Isaksson et al. / J. B io medi cal Science and Engineering 4 (2011) 200-206
202
poly-L-lysine. Our aim was to investigate the effect with
a decreasing amount of the antiadhesive cation-anion
complex. The animals were randomly divided into
groups as shown in Table 2. The substances were in-
stalled intra-abdominally and in the same sequence as
described above.
2.4.3. Third Part
In the last part of the experiment we studied the possible
toxicity of epsilon poly-L-lysine when administered
alone, without the neutralizing poly-L-glutamate. Four
different concentrations were tested in twenty animals,
divided in four groups with five animals in each (Table
3). The exper iment started with the lowest concentration.
2.5. S tatistical Analysis
Values are given as means (SEM). The non parametric
Kruskal-Wallis test was used to compare differences in
adhesions between the study groups and the Mann-
Whitne y U-test to determine changes between individual
groups. A p-value less than 0.05 was considered statis-
tically significant. For these statistical analyses SPSS®
version 17 (SPSS Inc, Chicago, I llinois) was used.
3. RESULTS
In the first part of the study, all animals survived and
fared well during the whole experimental period. Epsilon
poly-L-lysine, lacto ferrin, lysozyme and polyarginine all
Table 2. Experimental design, part two. Different concentra-
tion of epsilon-PL.
Grou p Animals
(N) Trea t ment Concentration (%) Volume (ml)
1 10 e-PL + PG 0.05 + 0. 05 1 + 1
2 10 e-PL + PG 0.01 + 0. 01 1 + 1
3 9 e-PL + PG 0.005 + 0.005 1 + 1
4 10 NaCl 0.9 2
*the abbreviations of the substances are the same as shown in Table 1.
Table 3. Experi mental design, part three. Toxicity study of
epsilon-PL.
Grou p Animals
(N) Trea t ment Concentration (%) Volume (ml)
1 5(3) e-PL 0.5 1
2 5(0) e-PL 0.1 1
3 5(0) e-PL 0.05 1
4 5(0) e-PL 0.01 1
5 7(0) NaCl 0.9 1
*the number within the parenth eses repres ents the number of animal/s that
died . **the abb r e v iations a re t he same a s shown in Tab le 1 above.
showed a significant better anti adhesive effect (p < 0.05)
as compared to the controls receiving sodium hydro-
chloride (Figure 1). As expected, the α poly-L-lysine
was significantly more effective (p < 0.001) than the
control group receiving sodium chloride. As seen in the
diagram, the most effective of the four substances tested
was epsilon poly-L-lysine, followed by polyarginin, ly-
sozyme and, in last place, lactoferrin. Epsilon poly-L-
lysine was equal to α-poly-L-lysine in its antiadhesive
effect and both were significantly better than the other
three cations.
In the second part of the study, where different con-
centrations of epsilon poly-L-lysine were tested, all ani-
mals fared well and showed no signs of adverse events
duri ng the whole expe ri ment. I n Fi g ure 2 , the results ar e
presented and there was a significant anti adhesive effect
in every concentration compared to the controls, except
Figure 1. Results of adhesion reduction with various cations in
com bi na ti on w it h polygluta m a t e . The dots re pre s e nt outlie r s .
Figure 2. Results of adhesion reduction with different concen-
trations of epsilon PL in combination with polyglutamate. The
dots represent outliers.

K. Isaksson et al. / J. Biomedical S cience and Engineering 4 (2 011) 200-206
Copyright © 2011 SciR es. JBiSE
203
for the lowest, p = 0.001, p = 0.002, p = 0.02 and p =
0.103 respectively.
In the third and last part of the experiment we studied
the toxicity of epsilon poly-L-lysine. All animals except
for three survived and fared well trou gh the whole stud y
period. Those three that died belonged to the group that
received the highest concentration of epsilon poly-L-
lysine, at 0.5%. The animals showed distress and inade-
quate rec over y b ut di d not s how a ny co nv ulsio ns a s t hey
did in the toxicity study of α poly-L-lysine [20]. An au-
topsy of the three animals did not show any signs of in-
traabdominal bleeding, signs of macroscopic infla mma -
tion or intestinal o bstr uction.
As pointed out above, all animals except for those
three mentio ned in the thi rd se ct io n far ed well d uri ng t he
study period. They were observed frequently during their
recovery. Food intake did not seem to be changed. The
mice were weighed before primary surgery as well as
before the evaluation and no changes were observed.
4. DISCUSSION
Polypeptides are a group of macromolecules that are
widely used today in biological research as drug carriers
and gene vectors and for their antimicrobial properties
[22-27]. T hey are water soluble, biodegradable and often
described as non-toxic for humans and the environment
[28].
In previous experimental studies we have shown the
strong postsurgical intraabdominal anti-adhesive effect
of differently charged polypeptides [16]. In our early ex-
periments we noted the optimal effect of the two oppo-
sitely charged polypeptides α-poly-L-lysine and poly-L-
glutamate, which creates a matrix that serves as a me-
chanical barrier for adhesion formation [16]. Previous
studies have also shown no effect on local immunologi-
cal functions, i.e . peritoneal macrophages, and a local
clearance of this biodegradable matrix within 4 weeks
[16,19]. The antiadhesive effect of the polypeptides is
based on electrostatic binding between the strong cation
poly-L-lysine and the negatively charged damaged peri-
toneum [29], and thereafter electrostatic bonds between
the poly-L-lysine and the anion poly-L-glutamate create
a mechanical barrier between damaged and adhesion-
prone pe ritoneal tissue. The polypeptide matri x accumu -
lates in areas of damaged peritoneum [16] and has also
been shown to aid in intestinal healing as well as de-
creasing parenchymal bleeding and possibly infla mma -
tion [17,18,30].
Due to reports of in vitro and in vivo toxicity using
cationic polymers for gene delivery and graft coating
[25,31-34] we performed a study on the intraabdominal
toxicity of single use of the cation α-poly-L-lysine [20].
This study showed a lethal toxicity in mice with the in-
traabdominal dose we had previously used. However, in
lower doses, the toxicity disappeared but the antiadhe-
sive effect was also diminished. The gap between no
toxicity and effect was declared too narrow and we aim
to find a less toxic cation to use within the concept of
pre ve nt i ng intra-abdominal adhesions with differently
charged polypeptides. Poly-L-glutamate, administered
alone, has in previous experiments shown that it is
non-toxic and even decreased adhesion formation, but is
not as promising as when used in complex with
poly-L-lysine [19].
In all our previous studies we have used the common
form of poly-L-lysine; the α-poly-L-lysine. The alpha
form is a long helix -shaped chain t hat elo ngate s whe n in
contact with the cell membrane. The alpha form carries
longer side chains than do most other polypeptides. We
hypothesized that due to the long side chains, the alpha
form penetrates, interacts and bursts the cell membrane,
causing immediate cell cytotoxicity[35-36]. This has
support in the literature, suggesting that the toxicity of
polypeptides and polycations in particular is not only
dose-dependent but also connected to molecular weight
and cationic charge density[37-38].
In the present study we have tried to examine other
cationic polypeptides with properties that we hypotheti-
cally need to create a strong anti-adhesive matrix but
still have a non-toxic environment, not only for the
combination of polypeptides but also for the polypep-
tides themselves. These polypeptides would preferably
be long enough that a strong matrix can be formed (size)
and have a cationic charge sufficient enough to interact
with, but not burst, the cell membrane (densi ty). F or this
test we used two linearly structured substances, i.e. ep-
silon poly-L-lysine and poly-L-arginine, and two globu-
lar structured substances, lactoferrin and lysozyme.
Epsilon poly-L-lysine is a natural substance from the
metabolism of Streptomyces albus, with the capacity to
inhibit growth of both grampositive and gramnegative
bacteria. It is widely used as a food preservative and is
also reported having an antitumoral effect [28,39-40].
Epsilon poly-L-lysi ne i s o f sho r te r l engt h and ha s s hor te r
sidechains than α-poly-L-lysine (Figure 3), and there-
fore, we hypothesize, carries less membrane cytotoxicity.
Poly-L-arginine is a well-known protein transduction
domain used to transport molecules i nto c e lls[41]. I t is o f
roughly the same size as α-poly-L-lysine. Lactoferrin is
also known as lactotransferrin. It is a globular multi-
functional glycoprotein that contains many polycation
domains. It has antimicrobial and anti-inflammatory
activity and is found in milk and many mucosal secre-
tions such as tears and saliva[42]. Lysozyme is an en-
zyme that is part of the innate immune system and, like
the previous substances, has an antimicrobial effect. It is
present in ma ny mucosal secr etions like lactoferrin.

K. Isaksson et al. / J. B io medi cal Science and Engineering 4 (2011) 200-206
204
Figure 3. Chemical structure of epsilon poly-L-lysine (at the
top) and alpha poly-L -lysine (at the bottom) with the mono-
mers presented within the brackets. (Isaksson K, Åkerberg D,
Said K, Tingstedt B)
In the pre se nt st udy we ha ve s hown that al l of the ne w
polycationic substances tested with poly-L-glutamate in
the experiment reduced the amount of adhesion forma-
tion significantly compared to the controls, further
strengthening the concept of the use of differently
charged polypeptides as a matrix barrier for postsurgical
adhesion control.
Epsilon poly-L-lysine was superior to polyarginine,
which in turn was more effective than lysozyme and
lactoferrin. This indicates that a polypeptide with a lin-
ear structure is better than one that is globular, probably
due to the fact the globular substances have their ionic
charges turned inward. The four-fold increase in the
conc ent ra tion of l yso z yme i n t his experiment is based on
its small size, but mostly due to its ball-like structure
that does not expose as much charge as the other sub-
stances. In previous studies we have also shown a de-
creased effect of α-poly-L-lysine when using smaller
size (shorter chains) [43] and also an effect, however
small, of lysozyme in a concentration of 1% [19]. By
increasing the concentration of lysozyme we hoped to
create enough molecules fo r strong ma tr ix fo r mati o n.
In the second and third part of the experiment we fo-
cused on the antiadhesive effect of epsilon poly-L-lysine,
which turned out to be equal to that of α-poly-L-lysine.
In the latter parts of the study a diminished antiadhe-
sive effect of epsilon poly-L-lysine was shown, as ex-
pected, with decreasing doses. However, epsilon poly-
L-lysine showed a significant antiadhesive effect in
combination with poly-L-glutamate 40-fold below toxic-
ity level as shown in part thr ee of the experime nt .
The toxicity of epsilon poly-L-lysine was 10-fold
lower compared to α-poly-L-lysine [28], most probably
due to the fact that it is smaller in size. Therefore epsilon
poly-L-lysine is promising as a polypeptide that could be
part of a future antiadhesive treatment, even though an
even lower toxicity level would be preferred.
However, there is still room for the development of
the concept of bioactive biodegradable oppositely charged
polypeptides as antiadhesive treatment.
One possibility might be to construct a premix of alfa
poly-L-lysine and poly-L-glutamate with an excess of
poly-lysi ne re s ult i ng in a one -d ose administration, where
the oppositely charged polypeptides are already bound to
each other, but with a net positive complex within toxi-
city levels. Another possible way could be to alter the
cationic polypeptid e to decrease the cationic charge den-
sity, or to alter it spatially.
5. CONCLUSIONS
In summary, we have further proven the antiadhesive
effect of using two oppositely charged polypeptides in
an experimental mouse model. The use of epsilon poly-
L-lysine as the cationic part is promising and needs fur-
ther attention, and studies along with para llel continuous
research for a more atoxic cationic polypeptide in the
setting of antiadhesive oppositely charged bioactive po-
lypeptides, preferably of smaller size and of lower ionic
densi ty. Studie s are ongo ing in vit ro for cytoto xic eval u-
ation and in vivo to examine the potential direct influ-
ence on the fibrosis-fibrinolysis balance. A new model is
being developed for testing lower concentra- tions and
volumes of the polypeptides used.
This study was performed in parts due to grants from
Craaford Stiftelser.
REFERENCES
[1] Ellis, H., Moran, B.J., Thompson, J.N., Parker, M.S.,
Wilson, M.S. et al. (1999) Adhesion-related hospital
readmissions after abdominal and pelvic surgery: A re-
trospective cohort study. Lancet, 353, 1476-1480 .
doi:10.1016/S0140-6736(98)09337-4
[2] Menzies, D. and Ellis, H. (1990) Intestinal obstruction
from adhesions—how big is the problem? Annals of The
Royal C oll e ge of Surgeons of E ng l an d, 72, 60-63.
[3] Tingstedt, B., A nde r s s on, E., Isaksson, K. and And ersso n ,
R. (2008) Clini c a l impac t of abdom i na l a dhes ions : What is
the magnitude of the problem? Scandinavian Journal of
Gastroenterology, 43, 255-261.
doi:10.1080/00365520701708626
[4] Witkowicz, J., (2008) Pol Arch Med Wewn. Mesothelial
Cell Transplantation. 118, 307-313.
[5] Liakakos, T., Thomakos, N., Fine PM, Dervenis C and
Young, RL., (2001 ) Peritoneal adhesions: etiology,
pathophysiology, and clinical significance. Recent ad-

K. Isaksson et al. / J. Biomedical S cience and Engineering 4 (2 011) 200-206
Copyright © 2011 SciR es. JBiSE
205
vances in prevention and management. Dig Surgery, 18,
260-273. doi: 10.1159/000050149
[6] Holmdahl, L., and Ivarsson, ML. , (1999) The role of
cytokines, coagulation, and fibrinolysis in peritoneal tis-
sue rep air. Eu ropean Journ al of Surgery, 165, 1012-1019.
doi: 10.1080 /11024159 9750 00 7810
[7] van Goor H, de Graaf JS, Grond J, Sluiter WJ, van der
Meer J, Bom VJ and Bleichrodt RP. (1994) Fibrinolytic
activity in the abdominal cavity of rats with faecal peri-
tonitis. British Journal of Surgery, 81, 1046-1049. doi:
10.1002/bjs.1800810740
[8] Scott-Coombes, D., W ha wel l , S. and Vipond, MN. (1995)
Human intraperitoneal fibrinolytic response to elective
surgery. British Journal of Surgery, 82, 414-417. doi:
10.1002/bjs.1800820346
[9] Reij nen, M.M., Bleichrodt, RP. and van Goor, H. (2003)
Pathophysiology of intra-abdominal adhesion and ab-
scess formation, and the effect of hyaluronan. British
Journal of Surgery, 90, 533-541. doi: 10.10 02 /bj s.41 41
[10] Ivarsson, M.L., Bergström, M., Eriksson, E., Risb erg. B.
and Holmdahl, L. (1998) Tissue markers as pred ictors of
postoperative adhesions, British Journal of Surgery, 85,
1549-1554.
doi: 10.1046/j.1365-2168.1998.00859.x
[11] Tingstedt, B., Isaksson, J. and Andersson, R. (2007)
Long-term follow-up and cost analysis following surgery
for small bowel obstruction caused by intra-abdominal
adhesions. British Journal of Surgery, 94, 743-748. doi:
10.1002/bjs.5634
[12] Tingstedt, B., Isaksson, K., Andersson, E., Andersson, R.
(2007) Prevention of abdominal adhesions--present state
and what's beyond the horizon? European Surger y Re-
search, 39, 259-268. doi: 10.1159/00010 25 91
[13] Johns, D.B., Rodgers, K.E., Donahue, W.D., Kiorpes,
T.C. and diZerega, G.S. (1997) Reduction of adhesion
formation by post-operative administration of ionically
cross-linked hyaluronic acid. Fertility and Sterility, 68,
37-42.
doi:10.1016/S0015-0282(97)81472-0
[14] diZerega, G.S., Verco, S.J., Young, P., Kettel, M., Kobak,
W.A., Martin, D. et al. (2002) A randomized, controlled
pilot study of the safety and efficacy of 4% icodextrin
solution in the reduction of adhesions following laparos-
copic gynaecological surgery. Human Reproduction, 17,
1031-1038. doi:10.1093/humrep/17.4.1031
[15] Muller, S.A., Treutner, K.H., Tietze, L., Anurov, M.,
Titkova, S., Polivoda, M. et al. (2001) Efficacy of adhe-
sion prevention and impact on wound healing of intrape-
ritoneal phospholipids. Journal of Surgical Research, 96,
68-74.
doi:10.1006/jsre.2000.6031
[16] Nehez, L., Tingstedt, B., Vodros, D., Axelsson, J., Lind-
man, B. and Andersson, R. (2006) No vel t reat ment in p e-
ritoneal adhesion prevention: protection by polypeptides.
Scandinavian Journal of Gastroenterology, 41,
1110-1117.
doi:10.1080/00365520600554550
[17] Tingstedt, B., Nehez, L., Axelsson, J., Lindman, B. and
Andersson, R. (2006) Increasing anastomosis safety and
preventing abdominal adhesion formation by the use of
polypeptides in the rat. International Journal of
Colorectal Disease, 21, 566-572.
doi:10.1007/s00384-005-0053-x
[18] Tingstedt, B., Nehez, L., Lindman, B. and Andersson, R.
(2007) Efficacy of bioactive polypeptides on bleeding
and intra-abdominal adhesions. European Surgical
Research, 39, 35-40. doi:10.1159/000098438
[19] Nehez, L., Vodros, D., Axelsson, J., Tingstedt, B., Lind-
man, B. and Andersson, R. (2005) Prevention of post-
operative peritoneal adhesions: Effects of lysozyme, po-
lylysine and polyglutamate versus hyaluronic acid.
Scandinavian Journal of Gastroenterology, 40,
1118-1123.
doi:10.1080/00365520510023332
[20] Isaksson, K., Åkerberg, D., Andersson, R. and Tingstedt,
B. (2009) Toxicity and dose response of in-
tra-abdominally administered poly-L-alpha-lysine and
poly-L-glutamate for post-operative adhesion protection.
European Surgical Research, 44,
17-22. doi:10.1159/000258654
[21] Holmdahl, L., Al-Jabreen, M. and Risberg, B. (1994)
Experimental models for quantative studies on adhesion
formation in rats and rabbits. European Journal of Sur-
gery, 26, 248-56.
doi:10.1159/000129342
[22] King, A., Strand, B., Rokstad, A.M., Kulseng, B., An-
dersson, A. et al. (2003) Improvement of the biocompa-
tibility of alginate/poly-L-lysine/alginate microcapsules
by the use of epimerized algi nate as a co ating. J ourn al of
Biomedical Materials Research A, 64,
533-539. doi:10.1002/jbm.a.10276
[23] Takei, Y., Maruyama, A., Ferdous, A., Nishimura, Y.,
Kawano, S., Ikeijima, K. et al. (2004) Targeted gene de-
livery to sinusoidal endothelial cells: DNA nanoassociate
bearing hyaluronanglycocalyx. The FASEB Journal, 18,
699-701.
[24] Geornaras, I., Yoon, Y., Belk, K.E., Smith, G.C. and So-
fos, J.N. (2007) Antimicrobial activity of epsi-
lon-polylysine against Escherichia coli O157:H7, Sal-
monella Typhimurium, and Listeria monocytogenes in
various food extracts. Journal of Food Science, 72,
M330 -334.
doi:10.1111/j.1750-3841.2007 . 0051 0.x
[25] Billinger, M., Buddeberg, F., Hubbell, J.A., Elbert, D.L.,
Schaffner, T., Mettler, D. et al. (2006) Polymer stent
coating for prevention of neointimal hyperplasia. Journal
of Invasive Cardiology, 18, 423-426.
[26] Li, C., Yu, D.F., Newman, R.A., Cabral, F., Stephens,
L.C., Hunter, N. et al. (1998) Complete regression of
wel l -established tumors using a novel water-soluble
poly-(L-glutamic acid)-paclitaxel conjugate. Cancer Re-
search, 58, 2404-24 09.
[27] Moroson, H. (1971) Polycation-treated tumor cells in
vivo and in vitro. Cancer Research, 31, 373-380.

K. Isaksson et al. / J. B io medi cal Science and Engineering 4 (2011) 200-206
206
[28] Shih, I.L., Van, Y.T. and Shen, M.H. (2004) Biomedical
applications of chemically and microbiologically synthe-
sized poly (glutamic acid) and poly(lysine). Mini Re-
views in Medicinal Chemistry, 4, 179-188.
doi:10.2174/1389557043487420
[29] Larsson, K. (1994) Lipids-molecular organizations,
physical functions and technical applications. The Oily
Press, Dundee, Scotland.
[30] Tingstedt, B., Nehez, L., Lindman, B. and Andersson, R.
(2007) Effect of bioactive polypeptides on leaking large
bowel anastomosis and intestines in the rat. Journal of
Inve s ti gati v e Surgery, 20, 229-235.
doi:10.1080/08941930701481288
[31] Morgan, D.M., Larvin, V.L. and Pearson, J.D. (1989)
Biochemical characterisation of polycation-induced cy-
totoxicity to human vascular endothelial cells. Journal of
Cell Science, 94, 553-559.
[32] Moreau, E., Domurado, M., Chapon, P., Vert, M. and
Domurad, D. (2002) Biocompatibility of polycations: In
vitro agglutination and lysis of red blood cells and in vi-
vo toxicity. Jour nal of Drug Targeti ng, 10, 161-173.
doi:10.1080/10611860290016766
[33] Sela, M. and Katchalski, E. (1959) Biological properties
of poly-alpha-amino acids. Advances in Protein
Chemistry, 14, 391-478.
doi:10.10 16/ S00 65 -3233(08)60614-2
[34] Kenausis, G., Voros, J., Elbert, D., Huang, N., Hofer, R.,
Riuz-Taylor, L. et al. (2000) Poly(l-lysi ne) -g-Po ly-(ethy-
lene glycol) layers on metal oxide surfaces: Attachment
mechanism and effects of polymer architecture on resis-
tance to protein adsorption. The Journal of Physical
Chemistry B, 104, 3298- 3309. doi:10.1021/jp993359m
[35] Andrews, D.W. and Ottensmeyer, F.P. (1982) Electron
microscopy of the poly-L-lysi ne alpha-helix. Ultrami-
croscopy, 9, 337-348.
doi:10.1016/0304-3991(82 )90 094-8
[36] Chittchang, M., Alur, H.H., Mitra, A.K. and Johnston, T.P.
(2002) Poly(L -lysine) as a model drug macromolecule
with which to investigate secondary structure and mem-
brane transport, part I: Physicochemical and stability stu-
dies. Journal of Pharmacy and Pharmacology, 54,
315-323.
doi:10.1211/0022357021778556
[37] Fischer, D., Li. Y., Ahlemeyer, B., Kriegelstein, J. and
Kissel, T. (2003) In vitro cytotoxicity testing of polyca-
tions: Influence of polymer structure on cell viability and
hemolysis. Biomaterials, 24, 112 1-1131.
doi:10.1016/S0142-9612(02)00445-3
[38] Lv, H., Zhang, S., Wang, B., Cui, S. and Yan, J. (2006)
Toxicity of cationic lipids and cationic polymers in gene
delivery. Journal of Controlled Release, 114, 100-109.
doi:10.1016/j.jconrel.2006.04.014
[39] Szende, B., Szokan, G., Tyiha, E., Pal, K., Gaborjanyi, R.,
Akmas, M. et al. (2002) Antitumor effect of lysine- iso-
peptides. Cancer Cell International, 2, 4.
doi:10.1186/1475-2867-2-4
[40] Shih, I.L., Shen, M.H. and Van, Y.T. (2004) Microbial
synthesis of poly(ε-lysine) and its various applications.
Bioresource Tec hn ol o gy, 97, 1148-1159.
doi:10.1016/j.biortech.2004.08.012
[41] Fuchs, S.M. and Raines, R.T. (2004) Pathway for polyar-
ginine entry into mammalian cells. Biochemistry, 43,
2438-2444.
doi:10.1021/bi035933x
[42] Steijns, J.M. and van Hooijdonk, A.C. (2000) Occurrence,
structure, biochemical properties and technological cha-
racterist ics of lactoferrin . British Journal of Nutrition, 84,
S11-17.
doi:10.1017/S0007114500002191
[43] Nehez, L., Ti ngstedt, B., Axels son, J. and Andersson, R.
(2007) Differently charged polypeptides in the preven-
tion of post-surgical peritoneal adhesions. Scandinavia
Journal of Gastroenterology , 42, 519-523.
.
doi: 10.1080 /00 3655 20 6009 88 204