In
addition to providing the currently available solutions,
Bridge to Life has licensed exclusive worldwide rights
from VitaTech, to unique liposomal technology that directly
delivers energy in the form of adenosine triphosphate
(ATP) to the cells. VitaTech's trademark for this technology
is VitaSol™.
Medical
scientists have long sought a way to deliver ATP directly
to cells. These efforts had been unsuccessful until
now. VitaTech has developed liposomal vesicles containing
ATP that have been demonstrated to deliver a high volume
of ATP to the cells.
Liposomal
technology involves a drug preparation that contains
the active substance in very tiny fat particles (natural
phospholipids), which provide improved distribution
with better cellular absorption. ATP is a chemical substance
(described below) by which cells store and use energy.
We believe that this technology has direct application
in organ transplant solutions and certain medical procedures.
As
part of the licensing agreement, BTL has specifically
secured the services of William Ehringer, Ph.D., the
inventor of the technology, to assist in the preclinical
and clinical development. Dr. Ehringer is Founder and
Chief Scientific Officer of VitaTech, Associate Professor,
Department of Physiology and Biophysics at the University
of Louisville, and Director, Center for Cellular Energy
Delivery, University of Louisville School of Medicine.
The delivery of cellular energy is the basic premise
of the technology. He brings an invaluable experience
base to our development program. In order to commercialize
his invention that Dr. Ehringer calls VitaSol™, he founded
VitaTech LLC, the licensor of the technology.
For
living cells to function they must have a continuous
source of energy and the energy that they use is in
the form of adenosine triphosphate (ATP). Cells manufacture
their own ATP by using glucose and oxygen that is broken
down into carbon dioxide and water in a process called
aerobic respiration. ATP is the biochemical way for
the cell to store and use this energy. Cells use this
energy both to maintain cell function as well as eliminate
waste products produced in the cell. Medical scientists
have long sought a way to deliver ATP directly into
cells. The hurdle has been that the cell membrane prevents
both entry and exit of ATP from a cell. VitaTech has
developed liposomal vesicles (lipid [fat] bubbles) containing
ATP that are able to transport a high volume of ATP
through the cell membrane. As a result, cells have a
ready source of energy to maintain cellular function
without the need to have access to oxygen or glucose,
such as in a stored organ awaiting transplant or a medical/surgical
procedure that restricts blood flow during the procedure.
The
use of liposomal technology is not new. The technology
has been demonstrated to work to allow active agents
to better penetrate the cell wall. There are two successfully
marketed products widely used for the treatment of systemic
fungal infections and in a product for treating cancer.
What is new and important is the use of liposomal technology
to deliver ATP to the cells.
The
photograph below (Fig 1) shows the ability of the liposomal
ATP to penetrate cell walls. A fluorescent dye was bound
to ATP and then the ATP was incorporated in liposomal
vesicles (VitaSol) to which epithelial cells (cells
in the topmost layer of tissues) were exposed. The photograph
shows the pickup and penetration of the ATP into the
cells. |
Figure
1
Fluorescent
dye bound to ATP Reveals Penetration of VitaSol through
cell walls |
| Animal
studies also have been conducted. In Figure 2, the infusion
of VitaSol™ compared to the St. Thomas solution (a solution
sometimes used during heart surgery) or empty vesicles
showed better blood flow through the arteries that supply
the heart muscle (coronary blood flow) that was maintained
for at least one hour and was more than 100% higher compared
to hearts perfused with St. Thomas solution or St. Thomas
solution with empty vesicles alone. These hearts had no
blood flow for one hour followed by the infusions. |
Figure
2
Infusion
from VitaSol Improves Coronary Blood Flow 100% vs.
St. Thomas Solution, a Solution that has Been Often
Used During Heart Transplantation Procedures
|
Isolated
rat hearts demonstrate better coronary blood flow following
a 1-hr no-flow. The hearts of three rats were surgically
removed, attached to a Lagendorf Isolated Perfusion
Apparatus, and allowed to equilibrate for 15-30 minutes.
Coronary blood flow from the heart was measured before
and then for 60 minutes after the 1-hr hypoxic ischemic
episode, i.e., the heart was deprived of oxygen for
one hour. VitaSol-treated hearts had significantly higher
coronary blood flow compared to St. Thomas solution
alone or St. Thomas solution containing lipid vesicles
only.
The
viability of the isolated rat hearts was further supported
by the fact that hearts that were infused with VitaSol™
had much higher oxygen consumption compared to the hearts
that received either St. Thomas solution or St. Thomas
solution containing empty lipid vesicles. Compared to
control, there was more than 100% increase in myocardial
oxygen consumption (Fig 3). |
Figure
3
Infusion
from VitaSol Improves Oxygen Consumption vs. St.
Thomas
|
Rat
hearts exposed to a 1-hr ischemic episode have higher
myocardial (heart) oxygen consumption rates when VitaSol™
is added to the perfusion media.
Rat
hearts that were infused with VitaSol™ were protective
from the hypoxic insult of potassium cyanide (KCN),
depriving the heart of oxygen (Fig 4). What these data
suggest is that if an isolated heart is infused with
VitaSol™ it is likely to survive longer and have better
function compared to an isolated heart that does not
receive the VitaSol™ containing ATP. |
Figure
4
Rat
Hearts Infused with VitaSol Survive Longer (and Have
Better Function) vs. Control After Subjection to Potassium
Cyanide
|
Sprague-Dawley
rat survival times at a fixed concentration of KCN (2
mg/kg).
The
survival times of the animals was recorded at a single
dose of KCN and in the presence of VitaSol injected
either into the arteries ( 5 mM ATP) or into the abdominal
cavity (20 mM and 50 mM ATP). VitaSol injected into
the arteries at 5 mM ATP did not significantly affect
rat survival times. In contrast, the animals that had
VitaSol injected into their abdominal cavity animals
at 20 or 40 mM ATP had significant increases in survival
time. *Control vs 20 and 40 mM ATP VitaSol, P<0.05,
n=6 (Six animals were tested.)
Initial
studies in rats indicate a doubling of liver preservation
times when using a solution containing ATP-vesicles
(VitaSol™) in conjunction with the UW Solution, over
what would be possible using solution alone.
Pilot
studies of the impact of adding liposomal ATP to UW
Solution™ on survival after prolonged storage of rat
livers were conducted. The rat livers were stored for
20 hours and then transplanted to rats and the recipients'
48-hour survival time observed.
Of
the rats transplanted with livers that had been stored
in UW Solution alone (7), only 2 (29%) survived after
48 hours. Of the rats that received livers stored in
UW Solution plus liposomal ATP (7), 6 of the 7 (88%)
survived. (Fig 5) |
Figure
5
|
| In
a related study, the effect of ATP-vesicles on composite
rat limb preservation was demonstrated. Limbs were perfused
with a standard physiologic solution and with the same
solution plus ATP-vesicles (liposomal ATP) for 13 hours
(Fig 6). |
Figure
6
Limb
Preserved via Perfused ATP for 13 Hours Before Transplantation
|
| Then twelve hours after transplantation, the limbs perfused with a solution containing ATP-vesicles (left) were viable versus those that were not exposed to the ATP-vesicles (right) that were necrotized (dead), as shown in the pictures below (Fig 7). |
Figure
7
Viable
Limb from Preservation by ATP Vesicles (Left) 12 Hours
After Transplantation vs. Necrotized Control; Living
Animal with Motor Functions (Bottom)
|
VitaSol™
has the promise to provide benefits to organ preservation
in two fundamental ways:
- Provide
critically needed energy at cell level during cold
storage.
- Aid
metabolic processes critical to reducing the level
of non-esterified fatty acids, which may exist as
a result of ethanol induced build up.
During
cold storage, cellular sources of energy decline and
toxic metabolites accumulate. As illustrated below,
if implantation ("reperfusion") occurs before energy
levels go below a critical threshold, the organ can
rapidly recover from this effect ("survival" conditions).
However, if energy levels are depleted by prolonged
storage or by impaired ATP at the initiation of surgery
(e.g., fatty liver), the organ cannot metabolically
recover from cold storage and primary nonfunction/dysfunction
occurs after implantation ("nonsurvival" conditions)
(Fig 8). |
The
Goal of UW + VitaSol |
Figure
8
 |
|
Use
of Liposomal ATP in Organ Transplantation
BTL plans
to develop the liposomal ATP technology as a substance
to be added to the UW Solution™ (The UW Solution™,
Belzer UW Solution™) at the time of use with a
goal of improving the length of storage time as well
as possibly improving outcomes in terms of organ rejections.
In liver transplants, the use of the liposomal ATP may
allow the use of less than ideal livers. Doing so would
help reduce the almost 18,000 patients waiting for liver
transplants. Among the pool of donated livers, about
25% are mildly to severely steatotic or fatty, most
of which are rejected by physicians because of the problems
associated with the fatty condition. These problems
associated with fatty liver are largely due to reduced
levels of ATP. If the problems with fatty liver could
be overcome, i.e., increase ATP levels, then more livers
could be accepted by transplant surgeons. As a result
more patients could receive transplants and some patients
who might die because not enough suitable livers were
available might survive.
-
The VitaSol animal model data support its great promise
as an agent for organ transplantation as well as in
certain cardiovascular procedures and tourniquet surgery.
All of these procedures or surgeries involve reperfusion
injury. The cardiovascular procedures include post
myocardial infarction (heart attack) approximately
1.5 million annually, stent procedures for blocked
heart arteries (the placement of wire devices in the
artery to keep it open), over 1 million annually,
and cardioplegic solution use to stop the contractions
of the heart in cardiac bypass surgery.
-
Reperfusion injuries are a well-known phenomenon in
heart bypass and other surgical procedures. Myocardial
infarction is caused by obstruction of one or more
coronary blood vessels (blockage of the heart’s
arteries) giving rise to ischemia in downstream areas
of the heart muscle. While coronary revascularization
(heart bypass surgery or placement of stents) is essential
to salvage ischemic myocardial tissue (oxygen-deprived
heart tissue), the re-establishment of blood flow
by interventional or surgical methods causes the formation
of oxygen radicals and an acute inflammatory response.
If unchecked, the inflammation leads to irreversible
damage to the heart muscle, limiting the success of
the reperfusion procedure. We believe that it is commonly
accepted that approximately 50% of overall tissue
damage is caused by reperfusion injury.
- Tourniquet
surgery refers to the use of pneumatic tourniquets
in more than one million surgical cases each year
in North America, more than half of which are for
orthopedic procedures. During surgery, the tourniquets
cut off the flow of blood to limbs for 30–90
minutes, during which time dangerous metabolic byproducts
build up. When the tourniquets are released, tissue
oxygen levels increase and what is called ischemia-reperfusion
injury may occur. Injuries range from minor damage
to skeletal muscle tissue to organ failure and even
death. VitaSol is intended help minimize tissue and
organ damage by protecting the cells in the absence
of oxygen by providing the ATP needed to maintain
cell and tissue viability. This will decrease the
buildup of the metabolic byproducts that can lead
to serious injury.
The
use of liposomal ATP to reduce the risks of tourniquet
surgery may be of particular value in diabetic patients.
It is well known that diabetics have severely compromised
circulation to the extremities that result in amputations.
This condition increases the risk from surgery in these
patients significantly.
A
substantial amount of preclinical and clinical studies
need to be done to bring this new therapy to the market.
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