Broad Question 1

3/5/2012 9:55:13 AM #

Current isolation protocols for exosomes are very lengthy, not relible, and require special equipment. Exosomes are still not clearly defined and there is definitely an overlap with other microvesicle types. There is an urgent need for novel isolation strategies, characterization, quantification, tracing and manipulation (eg loading with siRNA cargo and use as vehicles for in vivo delivery). Exosomes clearly have tremendous potential for basic research as well as diagnostics and therapautics applications, but the basics needs to be addressed first.

Alexander Vlassov | Reply

3/6/2012 11:41:54 AM #

Specific definitions need to be developed to clearly identify what kind of particle constitutes an exosome or a microvesicle and this may need to be cell type specific (may also change with age, sex, and disease state).

Mervin Yoder | Reply

3/6/2012 5:22:39 PM #

Cell-derived particle populations (both natural and induced exosomes or microvesicles) would be best defined at the single particle level, including biochemical composition, molecular structure and function.

Gus Rosania | Reply

3/8/2012 6:10:52 AM #

Besides the challenges in exosome isolation and definition, another one is the yield of exosome generation. To utilize the exosome as a drug carrier, a method that could improve the yield is also highly desired.

Chenjie Xu | Reply

3/14/2012 6:39:28 AM #

Vesicles are best initially defined by their biologic actions and their cells of origin. they will be inherently heterogeneous but this does not diminish their potential or significance. the can be defined by general surface epitopes but agasion this may be misleading. The debate about micovfesicle versus exosome leads no where and should be dropped.

peter quesenberry | Reply

3/19/2012 1:42:37 AM #

It is essential to know the role of exosomes in diseases such as in cancer metastasis and how one can target these to prevent the spread of cancer.

Vinod Labhasetwar | Reply

3/20/2012 2:47:35 AM #

Lots of interlab comparisons must be made to understand and exploit exosomes and other extracellular vesicles. Thus we need concensus methods to purify and characterize them. Production and collection will vary from system to system.

Catherine Fenselau | Reply

3/20/2012 4:24:08 AM #

Still purification of exosomes from samples (cell culture media or biological fluids) is time consuming, unreliable and based on physical methods (mostly ultracentrifugation). The only alternative is immunocapturing (currently under development). Exosomes still need clear definition and characterization. Their role in human physiology and in diseases has to be mostly addressed. New methods to both quantify and characterize  exosomes are needed. Exosomes have huge potential for diagnostic and therapeutic applications, once the above issues will be satisfactorily addressed.

Antonio Chiesi | Reply

3/22/2012 2:16:04 AM #

One of the greatest unmet needs in the field is to understand the different subgroups of extracellular vesicles regarding their origin, distinct functions and isolation/separation. Clearly, phenotype shifts of a cell also changes the profile of the extracellular vesicles it releases, which may explain a lot of their biological functions.

Understanding how to distincly eliminate or influence the RNA orin exosmoes and microvesicles, to determine the role of this specific cargo, would substnatially increase the understanding of the core mechanisms of extracellular vesicles.

Further, understanding how to efficiently load RNA into exosomes may increase the possibility of achieving the goal of using exosomes as vectors for treatment with siRNA in disease. If that could be achieved, a therapy should be possible to launch within a few years, at least in severe orphan diseases.

Jan Lötvall | Reply

4/30/2012 11:59:54 AM #

Yes, there is a need for a standardized protocol that would define an exosome or a microvesicle. More importantly though if we must acquire skills for manipulating the content of an exosome, we must understand the biogenesis of an exsomes in minute details. There has to be a distinction made in the cargo and the candidates that are essential to the biogenesis. Although much is known there is a lot to be understood about exosome biogenesis. Considering how cells grow and differentiate it is possible that there isn't one specific pathway  - understanding biogenesis in one cell type may not be applicable generally - thus there is a need to learn about exosome biogenesis in varied cell types and under varied physiological and developmental  paradigms. Heterogeneity of an exosome - in its content and in its biogenesis are two important challenges that must be met right away.

Suraj Bhat | Reply

5/31/2012 9:58:34 AM #

What are the major obstacles and challenges in exosome and microvesicle research?
•  How to evaluate the role of exosomes in specific disease states
•  How to modulate exosome content and evaluate the effect of these changes on exosome function (e.g. on inducing an inflammatory or T cell response)
•  We are limited in our ability to follow exosomes in vivo and to identify the origin these exosomes.  

What is needed to overcome these obstacles and challenges?
•  Mechanisms to selectively knockout exosome release in a cell/tissue specific manner
•  A better understanding of how components are trafficked to exosomes and approaches to manipulate the process
•  Develop tools to express exosomes in vivo which can be visualized over time

Jeff Schorey | Reply