MEDICAL RESEARCH SOCIEW
Communications for the Spring Meetlng of the Medical Research Society on I 9 May I999 at the Royal College of Physicians, London
MRS Communications
MI. '(1-11, I I U Ipokcn
IiMII and Y W I O Porten
M I LIVER CELLS TRANSPLANTED INTO THE RAT
PERITONEUM
PROLIFERATE
AND
EXHIBIT
DIFFERENTIATED FUNCTION OVER SEVERAL MONTHS
C SELDEN, A CASBARD AND HJF HODGSON
The Liver Group, Dept. of Medicine, Imperial College School of
"
0
Medicine, Hammersmith Campus, Ducane Rd, London W12 .
Isolated hepatocytes can be transplanted into rat spleen or liver,
where they survive and proliferate. However, as a potential
therapeutic route or for experimental gene therapy, these sites are not
ideal. Previous attempts to colonise the peritoneum using purified
populations of hepatocytes have been unsuccessful. We hypothesised
that hepatocytes transplanted together with the non-parenchymal
population (npcs) of the liver would survive and proliferate in the
peritoneum. Methods: Liver cells were prepared by in-situ
collagenase perfusion of adult male inbred August rats; single cells
were obtained by filtration (56um mesh), and injected directly into
the peritoneum. Groups of 6 animals were sacrificed at 1 week, 1, 3,
6 and 9 months. Abdominal tissues were fixed in formalin and
methacam, and stained with H&E, PAS for glycogen, and
immunocytochemistry. Results: Using this mixed population of
liver cells containing both hepatocytes and npcs, there was
macroscopic evidence of hepatocyte survival from 1 week to 9
months, in the fatty tissue surrounding the pancreas and lying
between the stomach and spleen. At one week there were mostly
single cells or doublets within the fat, which proliferated to islands of
hepatocytes with time, with obvious mitoses. The ectopic liver cells
had a granular eosinophilic cytoplasm, and were identified with a
specific anti-hepatocyte antibody. These hepatocytes were functional,
as evidenced by glycogen accumulation.
Proliferation was most
obvious at 3 months; but the cells remained viable and functional for
>9 months. Macrophages were evident within the areas of hepatocyte
implantation. Conclusions: This study demonstrates the importance
of the non-parenchymal cells in maintaining the survival and function
of hepatocytes, in areas which would be. suitable for testing
experimental gene therapy protocols, or for eventual clinical use.
M2 THE EFEFCTS OF SEX HORMONES ON ISOLATED
RAT MESENTERIC ARTERY TONE
P SEKRAHAN, D OTTER and C AUSTIN
Department of Medicine, Manchester Royal Infirmary, Oxford
Road, Manchester, M13 9WL, England.
Oestrogens have a direct vasodilatory effect on isolated rat small
arteries (Otter and Austin, J Pharm Pharmacol 1998; 50: 531-538).
The direct effects of other sex hormones on the vasculature are,
however, unclear. The present study therefore investigates, and
directly compares, the effects of 17 P-oestradiol, progesterone and
testosterone on isolated rat mesenteric artery tone. The influence of
nitric oxide and prostaglandins on responses was also studied.
Isolated pieces of rat mesenteric arteries (diameter = 292 k I3
pm) were mounted on a wire myograph, bathed in Krebs solution
(pH 7.4, 37OC, 95% air/5% CO2) and pre-contracted with 60 mM
KCI. Responses were obtained to either 17 0-oestradiol, progesterone
or testosterone (0.01-30 pM) in the presence and absence of L-nitro
arginine L-NA (50 pM) and indomethacin (10 pM), inhibitors of
nitric oxide and prostaglandin synthesis respectively.
All three agents relaxed pre-contracted arteries. At each
concentration responses to 17 P oestradiol and progesterone were
similar being respectively, for example, 4.54 f 2.34 and 3.52 f
3.84% for 1 pM. 24.43 k 1.92 and 16.85 f 5.69% for 3 pM, 53.90 f
7.09 and 42.56 2 7.52% for 10 pM and 80.45 f 5.72 and 78.19k
6.59 % KCl max. for 30 pM. The magnitude of the relaxation
observed to testosterone at similar concentrations was, however,
significantly less being 0,4.93 f 1.13, 17.28 f 5.09 and 40.09 2
7.61% for 1,3, 10 and 30 pM testosterone. Incubation with L-NA and
indomethacin had no effect on the responses observed to any steroid.
Thus, 17 P-oestradiol, progesterone and testosterone all
directly relax isolated rat mesenteric arteries via a mechanism(s)
which is independent of nitric oxide and prostaglandins. Mesenteric
arteries were less sensitive to the vasodilatory effects of testosterone
than to 17 P-oestradiol and progesterone.
M3 INITIAL CLINICAL EXPERIENCE WITH SMALL
VESSEL CORONARY STENTING
N MELIKIAN, TP CHUA, L D E N " , J CLAGUE' and U
SIGWART'
Department of Medicine, Hammersmith Hospital, Du Cane Rd, London W12
ONN, England and *Departmentof Cardiology,Royal Brompton and Harefield
Hospital Trust, Sydney Street, London SW3 6". London
Coronary stenting in small vessels may be complicated by a higher incidence
of subacute thrombosis and a high restenosis rate. With the recent clinical
availability of 2.5 mm coronary stents and the routine use of ticlopidine, we
report our initial experienece in the use of coronary stents in small vessels. We
retrospectivelystudied 62 consecutivepatients (50 men; age 61 (9.6) years) in
a 5-month period between November 1997 and March 1998. Thirty one
patients were elective admissions, 28 with unstable angina and 3 with acute
myocardial infarction. Seventy three coronary angioplastieswere performed in
vessels <3.0 mm diameter. Of these, forty seven 2.5 mm coronary stents were
deployed in 38 patients (30 recoil, 14 dissection, 1 abrupt closure, 2 restenosis;
22 Multilink, 18 NIR, 7 GFX stents). Thirty five were deployed in the lee
anterior descending artery, 7 in the circumflex artery and 5 in the right
coronary artery. The immediate angiographic outcome was good in all except
for 5 patients (13.1%) (3 dissections (2 sustaining myocardial infarctions, 1
had emergency operation), 1 with poor distal flow and 1 with occluded
diagonal side branch). All these patients received aspirin and ticlopidine.
There was no subacute stent occlusion. In the patients with succcrsft~Isent
deployment, angina recurred in 8 patients (24.2%) alter a minimum follow up
of 6 months (mean 6.8 months). In the 24 patients who had small vessel
angioplaty (2.5mm balloon) wifhour stent deployment, 8 (33%) had
suboptimal results ( 5 recoil, 3 dissection; none suffered post procedure
infarction). Atter a minimum follow up of 6 months (mean 6.7 months), I 1
(45%) of these patients had recurrent angina @==0.04, Chi squared 4.1 17).
From our results, subacute stent thrombosis does not appear to be a major
complicationof small vessel coronary stenting when there is concurrent use of
aspirin and ticlopidine. Although the recurrence of angina appears more often
than in patients with larger vessel coronary stents, this remains less than in
those who received angioplasty alone. Coronary stents in small (2.5 mm)
vessels should therefore be deployed when indicated.