1. Jennifer Lei
  2. http://www.igert.org/profiles/4512
  3. Graduate Student
  4. Presenter’s IGERT
  5. Georgia Institute of Technology
  1. Torri Rinker
  2. http://www.igert.org/profiles/4914
  3. Graduate Student
  4. Presenter’s IGERT
  5. Georgia Institute of Technology
Judges’ Queries and Presenter’s Replies
  • Icon for: Jerome Baudry

    Jerome Baudry

    Judge
    Faculty: Project Co-PI
    May 20, 2013 | 03:14 p.m.

    Hello, could you clarify your goals: are you working on creating or improving bio-materials to mimic tissues? Is your goal to compare the properties of hydrogel and GAGs?
    JB

  • Icon for: Jennifer Lei

    Jennifer Lei

    Lead Presenter
    May 21, 2013 | 11:25 a.m.

    That is a great question! In our lab, we are able to utilize biomaterials and stem cells in a versatile manner. The goals on this poster are 2-fold, 1) We show that biomaterials can be utilized to better understand mesenchymal stem cell/adipocyte/osteoblast interactions in a disease state (i.e. diabetes), while not necessarily mimicking tissue, and 2) We show that mesenchymal stem cells can be manipulated (i.e. forced into aggregates) and modified with therapeutic agents (i.e. GAGs) as a cell-based therapy for different pathologies.

    Coming back to your specific question, we are not looking to compare the properties of hydrogels and GAGs, rather we utilize both for different orthopedic applications.

  • Icon for: Govindarajan Ramesh

    Govindarajan Ramesh

    Judge
    Faculty
    May 21, 2013 | 10:54 a.m.

    Nice work, The 10 min exposure to UV source, will it not change the cell characteristics, especially DNA damage or activation of certain transcription factors?
    b) What is the ratio of cell density to the hydrogel and photo initiator?
    c) Have you performed viability and proliferation studies on MSC spheroids coated with heparin?

  • Icon for: Jennifer Lei

    Jennifer Lei

    Lead Presenter
    May 21, 2013 | 11:42 a.m.

    Thanks for the questions! It has been found in many experiments that the UV light for such a short exposure time does not negatively impact cell viability. The part of the polymerization process that is most harmful to the cells is the free radicals generated from the photoinitiator. To ensure that we do not seriously decrease cell viability, we use a very low concentration (0.05%) of photoinitiator and keep our exposure time to 10 minutes or less. We have found that we usually achieve 75-90% viability, which is standard in the field.
    b) Our cell density is usually about 100 million cells/mL and our photoinitiator, like I mentioned, is 0.05% of the precursor hydrogel solution. For instance, in a 100 uL hydrogel precursor solution, we have 1 million cells and 0.05 uL of the photoinitiator.
    c) We have performed viability studies on the heparin-coated MSC spheroids and we’ve seen that the cells are not negatively affected by this coating treatment and that the viability of the coated cells are comparable to the viability of the non-coated cells. We have not performed proliferation studies yet because in our experience, we have seen that the MSCs do not proliferate once aggregated into spheroid form unless treated with specific growth factors.

  • Icon for: Markus Seeliger

    Markus Seeliger

    Judge
    Faculty: Project Co-PI
    May 21, 2013 | 11:37 a.m.

    What orthopedic applications are you thinking of for your technology?

  • Icon for: Torri Rinker

    Torri Rinker

    Co-Presenter
    Graduate Student
    May 21, 2013 | 11:43 a.m.

    For our hydrogel-based platform to study cellular communication, we have studied diabetes, as you can see in the poster, and we are considering another study involving rheumatoid arthritis or another disease involving the joint.

    For our spheroid culture, we are looking at cell-based therapies that can treat cartilage or tendon defects.

  • Icon for: Zhaomin Yang

    Zhaomin Yang

    Judge
    Faculty
    May 21, 2013 | 08:17 p.m.

    What were normal and high glucose conditions and why was the effect of glucose examined?

  • Icon for: Torri Rinker

    Torri Rinker

    Co-Presenter
    Graduate Student
    May 21, 2013 | 08:46 p.m.

    We were interested in understanding more about cellular interactions in a disease state, specifically diabetes. Thus, since a consequence of diabetes is hyperglycemia (high levels of glucose), we chose to use both normal and high glucose levels for our experiments. The actual levels were determined based on previous literature and was either 1 g/L (normal) or 4 g/L (high).

  • Icon for: Kristin Hager

    Kristin Hager

    Judge
    Partner: Outreach
    May 21, 2013 | 08:40 p.m.

    Hi Heather,
    Interesting work and great explaination of biomaterials. Would you please explain Figure 1? It looks like you using a vital dye, and also staining nuclei Fig 1D. How does interpretation of E and F support your conclusion, that heparin coating does not compromise viability?

  • Icon for: Jennifer Lei

    Jennifer Lei

    Lead Presenter
    May 22, 2013 | 12:11 a.m.

    Thank you for your question! Figure 1 characterizes the heparin coating on our MSC spheroids. The heparin used to coat the spheroids is tagged with Alexa Fluor 633 and does not interfere with the LIVE/DEAD imaging. Figures 1A and 1C represent LIVE/DEAD staining for the negative control and the heparin coated spheroids, respectively. Figures 1B and 1D image the actual heparin coating (not nuclei) through the AlexFluor tag for the two groups mentioned above. Figures 1E and 1F are also imaging the heparin-AlexaFluor coatings on the MSC spheroids, however, in a red channel and at the different coating concentrations of 5mg/mL and 10mg/mL, respectively. The vital dye (LIVE/DEAD) seen in 1A and 1C show that the coating does not compromise viability.

Presentation Discussion
  • Icon for: Joni Falk

    Joni Falk

    Faculty: Project PI
    May 23, 2013 | 04:33 p.m.

    Very much enjoyed this inside look into the methodical work that goes on inside your lab. Thanks for sharing it!

  • Icon for: Jennifer Lei

    Jennifer Lei

    Lead Presenter
    May 24, 2013 | 02:24 p.m.

    Thanks!

  • Hsiu-mei Liao

    Guest
    May 24, 2013 | 01:19 a.m.

    Good job, Jennifer.

  • Icon for: Jennifer Lei

    Jennifer Lei

    Lead Presenter
    May 24, 2013 | 02:24 p.m.

    Thank you!

  • Further posting is closed as the event has ended.