Fall 2009 Junior Colloquium Team Members (in alphabetical order): Elizabeth Chen Charles Chiang...
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Transcript of Fall 2009 Junior Colloquium Team Members (in alphabetical order): Elizabeth Chen Charles Chiang...
Fall 2009 Junior Colloquium
Team Members (in alphabetical order):
Elizabeth Chen Charles Chiang
Elyse GeibelSteven Geng
Stevephen HungKathy Jee
Angela Lee
Christine LimSara Moghaddam-
Taaheri Adam Pampori
Kathy TangJessie Tsai
Diana Zhong
Team Mentor: John P. Fisher
The Organ Shortage
There are over 100,000 people are on organ donor lists
Only 77 of these patients receive transplants daily
Hearts are limited to 4 hours in storagePreservation-related injury
Organ Storage Today Static Cold Storage
University of Wisconsin SolutionNo significant improvements in last two
decades Continuous Perfusion
Organ Care SystemEffective, but extremely expensive
Overall Objective Idea: To modify clinical cold storage
procedures in place using hydrogen sulfide (H2S)
H2S is a compound thought to induce suspended animation and prolong organ storage
NaHS reacts with water to form H2S
Hydrogen Sulfide H2S is depleted from solution
H2S metabolized by tissues
Since H2S is a gas, it escapes from solution quickly
Limited protection time due to this depletion
As a result, need to control delivery of H2S treatment
Controlled Drug Delivery Hydrogels – polymer networks
Gelatin Crosslinking Size of microspheres
Hypothesis
Gelatin microspheres can sustain H2S levels in the heart and induce protective effects
Objective IH2S & Cells Objective: To determine if heart
cells metabolize H2S and how they are affected by H2S
Methods:After incubation, aqueous H2S levels will
be measured using a Zinc Acetate assayOther assays to determine cell viability
Objective INaHS Dosage Test
Objective: What is the most effective concentration of NaHS for storage solutions?
Methods:0 to 100µM NaHS in UW solutionSample at 2, 4, 6, 8 hours
○ Cellular viability assays○ Functional evaluation
Objective IISustaining Release of H2S Objective: To determine if gelatin
microspheres can release H2S in a controlled fashion
Method:Vary crosslinkageDetect change in release rate using zinc
acetate assay
NaHS in UW
solution
Rat heart submerged in
NaHS loaded UW solution
UW solution
Rat heart submerged in UW solution
Objective IIIEffects of Sustained Release
Objective: To determine the effect of sustained H2S on heart storage
Methods:H2S microspheres added to UW solution
Stored at 4ºC for eight hoursBiopsy at 2, 4, 6, 8 hours
○ Cell viability assays○ Functional evaluation
NaHS in UW
solution
Rat heart submerged in NaHS loaded UW
solution and injected with NaHS loaded
microspheres
NaHS loaded microsphere
PBS loaded microspher
es
Rat heart submerged in NaHS loaded UW
solution and injected with PBS loaded
microspheres
NaHS in UW
solution
Current Progress Funding Review Paper IACUC application has been submitted
to UMD School of Medicine Cell Culture
Obtained H9c2 cells, a rat heart cell lineCultured these cells into a suitable
populationWill start experiments shortly.
Microsphere Fabrication Fabricated microspheres
by spraying the gelatin solution into an oil/water emulsion
Currently capable of making microspheres at 4±2µmOutliers greater than 10µm
are excluded by means of a filter
Crosslinking Crosslinking by adding gluteraldehyde
to the gelatin solutionCrosslinking amount will be controlled by
altering the gluteraldehyde concentration Once crosslinked, the microspheres are
loaded with the NaHS solution
H2S Release H2S release will be measured via a zinc
acetate assay
50uL
50uL PBS
Repeat for each time point
Initial loading concentration of 6.7M NaHS, 1M gluteraldehyde
Net H2S Released Over Time
In Conclusion
Team Dynamics Big group:13 people on the team
Split into subgroups for efficiency Rotate facilitators during meetings to
divide leadership Be realistic
Learn to accept setbacks
THE END Any questions?
Global Hypothesis (Detailed)
Gelatin microspheres used to administer controlled delivery of H2S to the heart will induce protective effects and cause a state of hibernation in order to prolong viability of the heart and reduce ischemia-reperfusion injury in transplants