regenerative medicine and stem cells

Regenerative Medicine and Stem Cells

Prof. Dimitrios Fotiadis

Unit of Medical Technology and Intelligent Information Systems

Department of Materials Science and Engineering

University of Ioannina

Contents

Introduction

Concentrations in the field of Regenerative Medicine

Tissue Engineering & Regenerative Medicine

Tissue Engineering & Biomaterials

Introduction Regenerative Medicine

A scientific field that focuses on new approaches to the autologous repair

and/or replacement of cells, tissues and/or organs

Renew or replace cells that have been damaged and lost function due to injury

or illness.

A potential to prevent birth deaths, retard damage to diseased tissues, enhance

the metabolic or biomechanical function of tissues and manipulate normal and

abnormal tissue growth processes.

Research in regenerative medicine occurs from the molecular level to clinical

applications.

RiAus PDplus: Regenerative medicine, riaus.org.au/pdplus


Cell and tissue engineering and its use in medical applications.

Development of new therapeutic approaches to prevent or treat a number of

diseases:

• stimulating the human’s body capacity to heal

• harnessing the potential of stem cells to regenerate tissues

• reprogramming of cells

2015 Robert R. McCormick School of Engineering and Applied Science, Northwestern University


The design of materials that are compatible with biological systems, that

release drugs and active biomolecules and that resorb, enables these

applications.

The intersection among the fields of biomaterials and regenerative medicine

occurs under the tissue engineering field.

Synthetic or biological scaffolds are often employed to transplant cells and

manipulate their transformation into a functional tissue or organ.

2015 Robert R. McCormick School of Engineering and Applied Science, Northwestern University


Biomaterials can be any materials, natural or synthetic, which are used

therapeutically to repair, restore or replace lost function.

Bioengineering focuses on the design and synthesis of novel biomaterials for

tissue engineering, biocompatible nanoparticles and biosensors.

Biomedical engineering involves the application of the principles and

techniques of engineering to the enhancement of medical science as applied to

humans or animals.

Biomedical engineering is applied in the development of medical and diagnostic

devices and drugs.

http://scitechnol.com/tissue-science/biomaterials-and-bioengineering.php


Biomedical engineering combines the materials, mechanics, design, modelling

and problem-solving skills employed in engineering with medical and biological

sciences.

Improvement of the health, lifestyle and well-being of individuals.

A whole spectrum of disciplines: bioinformatics, medical imaging, image

processing, biomechanics, biomaterials and engineering, system analysis etc.

Successful application of biomedical engineering in the development and

manufacture of biocompatible prostheses, medical devices, image equipment

and pharmaceutical drugs.

http://scitechnol.com/tissue-science/biomaterials-and-bioengineering.php

Introduction Stem Cells

They have the potential to develop into many different cell types in the body

during early life and growth.

Three types of stem cells: (i) adult stem cells, (ii) embryonic stem cells (ES) and

(iii) induced pluripotent stem cells (iPS).

Stem cells are central to the regeneration process: cell-based therapies to treat

diseases.


Introduction Stem Cells

Given their unique regenerative abilities, stem cells offer new potentials for

treating diseases, such as diabetes and heart disease.


Introduction Regenerative Medicine Achievements

Hopes for the medical applications of stem cells are high.

Their ability to develop into any kind of cell in the body

holds as a huge potential to treat a range of human disea-

ses.

iPS cells are being used to model diseases for research

and drug development purposes.

Due to their patient-specificity, tissues grown from iPS cells would not be

rejected by the body’s immune system.


Introduction Regenerative Medicine Limitations

Since iPS cells are genetically modified, thorough investigations regarding their

safety are necessary before they can be used for patient therapy in the form of

tissue raplecement.

There is a little doubt that regenerative medicine offers exciting promise for the

future.

However, significant technical and ethical hurdles remain that will need to be

overcome if we are to see it reaches its full potential.


Concentrations in the field of Regenerative Medicine Medical Devices and Artificial organs

Artificial organs can sustain patients during their long wait for donor organs and

sometimes eliminate the need for transplantation altogether.

Artificial organs that perform the function of natural organs can help alleviate

this problem as well as sustain patients with organ failure as they await donor

organs.

McGowan Institute for Regenerative Medicine, http://www.regenerativemedicine.net

Concentrations in the field of Regenerative Medicine Tissue Engineering and Biomaterials

The goal of regenerative medicine is to one day be capable of maintaining the

body in such a way there will be no need to replace whole organs.

Possibilities of tissue engineering to replace, repair, maintain and/or enhance

tissue function for clinical use.


Concentrations in the field of Regenerative Medicine Cellular Therapies

Cellular therapies and stem cells can act as a repair mechanism for tissues lost

to trauma, disease, and wear and tear.


Concentrations in the field of Regenerative Medicine Clinical Translation

Clinical translation puts promising therapies into active trials.

Regenerative medicine is making great progress in the advancement of

medicine.



Tissue engineering is the application of the principles and methods of

engineering and life sciences toward the fundamental understanding of

structure-function relationships in normal and pathologic mammalian tissue

and the development of biological substitutes to restore, maintain or improve

function. (Fundamentals of Tissue Engineering and Regenerative Medicine,

Springer 2009)

The persuasion of the body to heal itself, through the delivery of the

appropriate site of cells, biomolecules and/or supporting structures. (Williams

Dictionary of Biomaterials, Liverpool Uni. Press 1999)

Dvir, Tal, et al. Nature nanotechnology 6.1 (2011): 13-22.


Tissue Engineering Product

Any product, involving cells, biomolecules and/or supporting structures that is

used in an ex vivo or in vivo process for the purpose of the regeneration of

tissue.

Tissue Engineering Process

Any process that is designed to take tissue engineering products and

manipulate them, either ex vivo or in vivo, in order to generate new tissue.

UK Centre for Tissue Engineering, David Williams


Creation of human tissue outside the body for later replacement.

Usually occurs on a tissue scaffold, but can be grown on/in other organisms.

Tissue engineers have created artificial skin, cartilage and bone marrow.


Tissue Engineering & Regenerative Medicine Elements

MATRIX (SCAFFOLD)

porous, absorbable synthetic or natural polymers

CELLS

differentiated cells of same type as tissue

stem cells

other cell types

REGULATORS

growth factors or their genes

mechanical loading

static vs. dynamic culture (bioreactor)

Massachusetts Institute of Technology, M. Spector, Ph.D.


Specific terms

A biomaterial is "any substance (other than drugs) or combination of

substances synthetic or natural in origin, which can be used for any period of

time, as a whole or as a part of a system which treats, augments, or replaces

any tissue, organ, or function of the body.

Biocompatibility — the ability of a material to perform with an appropriate

host response in a specific application.

Host Response — The response of the host organism (local and systemic) to the

implanted material or device.

www.biomat.net


Biocompatibility Primarily a surface phenomenon

www.biomat.net


Scaffolds & Microenvironments

Develop scaffolds that create synthetic microenvironments providing 3D

supports in order to control and direct the cellular behavior.

Properties affecting a scaffold’s utility include:

biocompatibility (no immunogenic and cytotoxic)

porosity and pore size (facilitate tissue integration and rapid vascularization)

appropriate surface chemistry to favor cellular adhesion, differentiation and

proliferation

mechanical properties

ability to integrate in the implantation site

Appasani K. and Appasani R., Stem Cells & Regenerative Medicine, Springer 2009


Scaffolds & Matrices

Synthetic degradable polymers

Natural biopolymers (proteins, polysaccharides)

Bioactive ceramics

Degradable / non degradable hybrids

Heterogeneity / anisotropy

Surface active / molecular release

Manufacturing technologies



The Role of Biomaterials

Tissue engineering is proving to be a revolution in biomaterials.

In the last century biomaterials were used for the fabrication of permanent

implants to replace tissue plants function (e.g., total joint replacement

prostheses).

In this century the principal role of biomaterials will likely be to serve as

scaffolds/matric for tissue engineering and cell and gene therapies.

The challenge in developing biomaterials as scaffolds for tissue engineering

appears to exceed the challenges in the recombinant production of growth

factors, and cell and gene therapies.



The Role of Biomaterials (Scaffolds)

Serves as a delivery vehicle for exogenous cells, growth factors, and genes; large

surface area.

Before it is absorbed a scaffold can serve as a matrix for cell adhesion to

facilitate/regulate certain unit cell processes (e.g., mitosis, synthesis, migration)

• the biomaterial may have ligands for cell receptors (integrins)

• the biomaterial may selectively absorb adhesion proteins to which

cells can bind




The scaffold serves as a framework to support cell migration into the defect

from surrounding tissues; especially important tissues; especially important

when a fibrin clot is absent.

May structurally reinforce the defect to maintain the shape of the defect and

prevent distortion of surrounding tissue.

Serves as a barrier to prevent the infiltration of surrounding tissue that may

impede the process of regeneration.




Khademhosseini A et al., Microscale technologies for tissue engineering and biology, National Academy of Sciences, 2006



Concepts Guiding the Development of Scaffolds

Biomaterials

• existing safe (“biocompatible”) absorbable materials; PLA—PGA

• natural extracellular matrix materials; bone mineral

• biomimetics and analogs of extracellular matrix; collagen and collagen--

hydroxyapatite scaffolds

• biopolymers for nanoscale matrix; self-assembling peptides

• new types of biomaterials designed specifically for tissue engineering

scaffolds




Concepts Guiding the Development of Scaffolds

Methods of Scaffold Production

• Precision (computer) multiscale control of material, architecture, and cells;

solid free-form fabrication technologies



Applications of Biomaterials

www.drsakthikumar.com


Problems/Test for Biomaterials

Acute toxicity (cytotoxicity) arsenic

Sub chronic/chronic Pb

Sensitization Ni, Cu

Genotoxicity

Carcinogenicity

Neurotoxicity

Immunotoxicity

Pyrogen, endotoxins

www.biomat.net


Evolution of Biomaterials

www.biomat.net

Structural

Functional Tissue Engineering Constructs

Soft Tissue Replacements


Biomaterials

An emerging industry

Next generation of medical implants and therapeutic modalities.

Interface of biotechnology and traditional engineering.

Significant industrial growth in the next 15 years - potential of a multi-billion

dollar industry.

www.biomat.net


Biomaterials

Challenges

To more closely replicate complex tissue architecture and arrangement in vitro

To better understand extracellular and intracellular modulators of cell function

To develop novel materials and processing techniques that are compatible with

biological interfaces

To find better strategies for immune acceptance

www.biomat.net

Tissue Engineering & Biomaterials Properties of Scaffolds

Change of Properties with Degradation

Physical

• overall size and shape

• pore characteristics: % porosity, pore size distribution, interconnectivity,

pore orientation




Chemical

• Biodegradability and moieties release; degradation rate synchronized to

the formation rate

• Provide or bind ligands that affect cell function




Mechanical

• Strength (and related properties, e.g., wear resistance)

• Modulus of elasticity; stiffness

Electrical and Optical ?


Tissue Engineering & Biomaterials Scaffolds

Structure – Architecture

Fiber mesh

Sponge-like

Fine filament mesh

Architecture by design; Free Form Fabrication/3-D printing



Structure – Architecture

Percentage porosity

• number of cells that can be contained

• strength of the material

Pore diameter

• surface area and the number of adherent cells

• ability of cells to infiltrate the pores

Overall shape of the device needs to fit the defect



Methods for producing scaffolds

Treat tissues/organs to remove selected components

Fibers (non-woven and woven)

Freeze-drying

Incorporate porogens into polymers

Self-assembling molecules

Free-form manufacturing



Pittsburgh Tissue Engineering (PTEI), http://www.ptei.org

Tissue Engineering & Biomaterials Scaffolds Materials

When designing a scaffold for tissue engineering the choice of the biomaterial is

of crucial importance.

Biomaterials investigated in regenerative applications can be divided into:

• natural (e.g. polylactic and polyglycolic acid and self assembling proteins)

• synthetic (e.g. fibrin, collagen, collagen-glycosaminoglycan copolymer )

• semisynthetic polymers


Tissue Engineering & Biomaterials Natural Biomaterials

Natural materials are obtained from natural sources such as collagen and

proteins of the extracellular matrix.

Collagen, a triple-helix protein, is one of the major components of the

extracellular matrix.

It provides support for connective tissue such as skin, tendons, and bone and

also interacts with cells in connective tissues.

It provides signals for cell adhesion, migration, proliferation, differentiation, and

survival.



Collagen is characterized by high mechanical strength, good biocompatibility,

low antigenicity, and the ability to be cross-linked.

It may be used in crude form or processed into porous sponges, gels, and sheets

and cross-linked with chemicals to make it stronger or alter its degradation rate.

The use of collagen matrix has been reported in several studies in peripheral

nerve and spinal cord regeneration and in tendon regeneration.

Other extracellular matrix molecules have also been used to prepare surface for

the culture and differentiation of stem cells.



Matrigel, a complex mixture of laminin, collagen IV, and heparin sulfate, is

largely used in in vitro culture systems.

Alginates isolated from brown sea algae form gels in the presence of bivalent

cations such as calcium.

They are biocompatible and inexpensive and for these reasons they have been

tested in tissue engineering applications.

The mechanical weakness and the poor cell adhesion stimuli in the case of

alginate scaffolds make this material not optimal for regenerative medicine

applications unless it is mixed with other strengthening materials such as

chitosan.



Despite their advantages, natural components face several challenges, as they

can induce inflammatory response.

Undefined factors that cannot be eliminated by purification prior to

implantation and pathogen transfer.

Other problems are the significant degree of variability among different lots and

the need for large-scale sources, particularly if human proteins are involved.



David J. Mooney & Eduardo A. Silva, Nature Materials 6, 327 - 328 (2007)

Tissue Engineering & Biomaterials Synthetic Biomaterials

Materials composed of synthetic components offer evident advantages such as:

• low immunogenicity

• reproducibility

• tailor ability of their mechanical and biochemical properties

These materials can be combined by reacting together to produce a wide range

of scaffolds exhibiting a mixture of the properties that are unique to each

individual material.



Optimizing these materials may lead to the development of reproducible,

scalable, nontoxic, and no immunogenic materials for expansion and

differentiation.

An important class of biomaterials is the class of poly(a-hydroxy esters).

Bioresorbable synthetic polymers that can be prepared in 3D scaffolds.

These biomaterials can biodegrade in the presence of water and carbonic

anhydride and show minor inflammatory response.



High-porosity scaffolds based on these biomaterials are often made of

microfibers and micropores.

This results in microenvironments in which cells grow in a two-dimensional

system.

In order to culture cells in a true 3D microenvironment, the dimensions must be

significantly reduced to nanometer dimensions.



Electrospinning represents an attractive technique for processing polymeric

biomaterials into nanofibers.

This technique offers the opportunity for control over the thickness and

composition of the nanofibers along with porosity of the nanofiber meshes.

In electrospinning, a strong electrical field is applied to a droplet formed from a

polymer solution.

The material to be electrospun is first dissolved in a suitable solvent to obtain a

viscous solution.



Meli L., Miao J. et al., Electrospinning from room temperature ionic liquids for biopolymer fiber formation, Green Chem., 2010,12, 1883-1892


The solution is passed through a spinneret, and a high-voltage supply is used to

charge the solution.

At a critical voltage, the repulsive forces of the charged solution particles result

in a jet of solution erupting from the tip of the spinneret.

Conventional electrospinning produces nanofibers that are randomly oriented.

The use of an electric field on the charged polymer solution makes it possible to

control jet trajectory, enabling the production of oriented nanofibers that can

be useful in the design of scaffolds for tissue engineering.



The electrospinning process is economical and simple, yields continuous fibers

and hollow fibers, and is versatile enough to be applied to a variety of materials.

Among the synthetic polymers intensively explored for the fabrication of

nanofibers are poly(glycolic acid), poly(lactic acid), poly(lactic-co-glycolic acid),

and poly(l-lactic acid).

In order to improve the stability and mechanical properties of scaffolds,

researchers have tested several tubular nerve guides.

These guides have shown negligible inflammatory response made of poly(l-

lactic acid)–caprolactone and poly(l-lactic acid)–poly(S-caprolactone) blends.



Other synthetic materials considered attractive scaffolds for tissue engineering:

• Hydrogels: insoluble hydrophilic polymers that have high water content and

tissue-like mechanical properties

Self-assembling peptides belong to this class of biomaterials.

The majority of the developed self-assembling peptides present hydrophilic

heads with hydrophobic tails or periodic repeats of alternations of hydrophilic

and hydrophobic amino acids.



Under physiologic conditions, ions screen the charged residues, and

hydrophobic residues of different b sheets can pack together via their

hydrophobic interactions in water, giving layered b-sheet nanofibers.

Alternatively, b-sheet structures can give rise to cylindrical nanofibers.

Self-assembling peptide scaffolds have a nanostructure with thin fibers (4–15

nm in diameter).

So, they resemble ECM-derived substrates such as Matrigel.



The formation of a scaffold and its mechanical properties are influenced by

several factors:

• hydrophobicity

• length of the peptide sequence

Approximately, the higher the hydrophobic residue content and the longer the

length of the peptide sequence, the stiffer is the scaffold.

One of the evident advantages of self-assembling peptides is that they are

composed of natural amino acids.



The degradation products of self-assembling peptides can be reused by the

body without eliciting a severe immune response.

These peptide scaffolds can be commercially synthesized and custom-tailored,

and they can be inexpensively and quickly modified.

Furthermore, self-assembling peptide scaffolds have recently become powerful

tools for regenerative medicine for:

• repair of myocardial infarction

• to stop bleeding as well as

• to serve as useful medical devices for slow drug release



Self-assembling peptides may be useful bioreabsorbable scaffolds for tissue

engineering applications.

However, self-assembled scaffold nanostructures are mainly randomly oriented

in three dimensions.

Randomly oriented monolayers have been obtained.

Further efforts have been undertaken to influence the formation of self

assembling structures via electromagnetic fields or microfluidic chambers.



This issue may be crucial in tissues in which a particular regenerated

cytoarchitecture has to be achieved at both the nanoscale and the microscale.

Another disadvantage of synthetic materials is the lack of cell-recognition

signals, and so they present few cellular interactions.

Efforts are being made to incorporate cell adhesion peptide motifs into

synthetic biomaterials.


Tissue Engineering & Biomaterials Semi-synthetic Biomaterials

The combination of synthetic materials with cell-recognition sites naturally

found in living systems is very attractive.

These hybrids materials could possess both the favorable properties of

synthetic materials and specific biologic activities.

As to self-assembling peptides, the simplest method for incorporating

functional motifs found in ECM proteins is to synthesize them sequentially

along with the self-assembling sequences.


Tissue Engineering & Biomaterials Semi-synthetic Biomaterials

Synthetic materials other than self-assembling peptides have been blended

with natural components.

Natural components can provide biochemical signals necessary to support cell

attachment, proliferation, and differentiation when blended with a synthetic

substrate.

Starting from these semisynthetic materials, it should be possible to develop

fully synthetic materials that avoid some of the challenges of using isolated

proteins



Tissue engineering has emerged as an excellent approach for the

repair/regeneration of damaged tissues.

Potential to circumvent the limitations of autologous and allogeneic tissue

repair.

Significant effort is still necessary to achieve a better understanding of stem cell

biology and an optimal microenvironment capable of stimulating transplanted

cells and host tissue regenerative “response”.

Developing functionalized scaffolds and choosing the appropriate set of

cytokines to be slowly delivered locally.



Considerable progress has been made toward understanding embryonic stem

cells.

However, we cannot claim they can be used safely in clinical applications.

At the same time, a number of challenges remain in the design of materials,

such as:

• no immunogenic

• scalable

• mechanically tunable

• bioactivity


Using Lab-on-a-Chip Technologies for Stem Cell Biology

The introduction of microtechnology and microfluidic platforms for cell culture

can dramatically enhance the pace of stem cell research.

With the use of microfluidic-based techniques, extracellular microenvironments

can be controlled in a precise manner, and their influence on various cellular

behaviors can be studied.

Microfluidic devices made of transparent materials allow real-time and high-

throughput monitoring of cell functions and cell fate by using fluorescence

microscopy and other optical techniques.



Stem cells reside in a complex biochemical and mechanical milieu and are

subjected to varied cues in the form of cell–cell, cell–matrix, and autocrine

signaling.

Conventional laboratory techniques for experimenting with stem cells include:

• tissue culture in plastic or glass cover slips

• gradient generation using micropipetting

• differentiation and self-renewal in tissue culture dishes or multiwell plates

• chemotaxis using Boyden chambers

• hanging droplet methods



With the advent of microfluidic platforms that mimic the in vivo complexity of

tissue organization and composition, stem cells can now be cultured.

Well-defined microenvironments and biochemico/mechanical and physical cues

can be provided in a spatiotemporally controlled and reproducible manner.

Besides miniaturization of conventional experimental methods, microfluidics

allows harnessing the advantages of physics.

Microtechnology provides a method for performing large-scale observations of

stem cell phenotypes and high-throughput cellular screening in response to a

combination of biochemical stimuli, extracellular matrix (ECM) interactions as

well as mechanical and physical stimuli.


Using Lab-on-a-Chip Technologies Microfluidic Lab-on-a-Chip

Microfluidics has emerged as an important tool for complementing or replacing

existing laboratory techniques.

The term microfluidics refers to the technology involving small amounts of

fluids perfusing engineered devices of varied complexity.

Experiments can be conducted with much greater control over the chemical

contents of the cellular environment and increased spatial and temporal

resolution.


Using Lab-on-a-Chip Technologies Microfluidic Lab-on-a-Chip meets Stem Cell Biology

Within the realm of microfluidics, all flows are essentially laminar.

Microscopic fluid streams travel in a continuous smooth and predictable

fashion.

A small particle moves within the fluid following the flow trajectory, distinct

from the frequent emergence of turbulent flow at the macroscopic scale.

Microfluidics also mimics the physiologic context of fluid flow present in

microvasculature.

A consequence of this is that transport of dissolved molecules between any two

laminar streams can occur only through passive diffusion rather than

convection.


Using Lab-on-a-Chip Technologies Working with Microfluidic Devices

Most microfluidic platforms for experimental analysis of stem cells are

fabricated by a process called soft lithography.



Lithography involves creating an embossed pattern containing small features on

substrates such as silicon or glass.

Coating them with a photosensitive chemical, or photoresist, that alters its

chemical properties upon exposure to ultraviolet (UV) light.

The pattern is created by controlling UV light exposure, usually using precisely

defined masks.

The embossed pattern containing the microscale features created by the

photoresist is used as a mold, and the replica of the pattern can be transferred

to a softer elastomer, typically made of polydimethylsiloxane (PDMS).



PDMS offers many advantages for stem cell analyses.

It is nontoxic to cells, impermeable to liquids, permeable to nonpolar

atmospheric gases, and optically transparent.

It is easily adaptable to standard optical imaging technologies, such as

fluorescence microscopy.

A standard microfluidic chip would be made up of a patterned slab of PDMS

that is reversibly bonded to a glass cover slip.

Thus, forming a chamber of microscopic dimensions for culturing stem cells.


Using Lab-on-a-Chip Technologies Investigating Stem Cell Biology

A microfluidic device can be designed to perform any multistep, conventional

biochemical experiment on a single platform.

This may lead to increased associated device and experiment complexity.

However, even simple designs allow one to conduct tasks not easily

accomplished previously, e.g., generating gradients of soluble materials or

automatically exposing cells to different reagents.

These advantages have allowed microfluidic technology to be used for various

biologic assays relevant to stem cell research.


Using Lab-on-a-Chip Technologies Investigating Stem Cell Biology

Engineering Stem Cell Microenvironment in Microfluidic Devices

Stem cells respond to various mechanical stimuli or alterations of the local gas

content that might also affect various systemic cellular properties.

One of the biggest advantages of using microfluidics for stem cells research is

the capability to create high-throughput experiments relying on highly defined

microenvironments.

Providing a physiologic context to the cells and to control experimental

conditions in a precise manner.


Using Lab-on-a-Chip Technologies Generation of Soluble Gradients

In vivo, cells frequently reside in spatial gradients of various stimulants.

Within the gradients, they frequently react by either differential responses to

local stimulant doses or directed movement or growth defined by the direction

of the gradients.

Key limitations in stimulating stem cells with relevant soluble factors:

• imprecise control of the concentration due to depletion of factors or

temporal and spatial instability of gradients

• lack of combinatorial interactions involving two or more factors with

different gradient profiles



An illustrative gradient-generating device



Combinatorial gradients involving multiple factors or a combination of soluble

and insoluble factors can also be created in two-dimensional surfaces or even in

three-dimensional gels.

Such microfluidically generated gradients of various morphogens have been

used to investigate stem cell phenotypes both in dose-response and

chemotactic studies.

Recent advances make it possible to make gradients of any arbitrary profile,

which can be tuned during the experiment.


Using Lab-on-a-Chip Technologies Generation of Insoluble Gradients

In addition to gradients of growth factors and cytokines, microfluidic devices

can be used to generate gradients of ECM molecules.

Aqueous solutions containing relevant ECM molecules can be flown into the cell

chamber to create the desired gradient by ECM deposition onto the glass from

the gradient-containing solution.

These gradients can be combined with gradients of soluble factors, creating a

combinatorial complex microenvironment better mimicking the complexity of

tissues.


Using Lab-on-a-Chip Technologies Conclusions

Microfluidics has brought a whole gamut of conventional laboratory techniques

to a single chip.

Introducing both sequential integration of multiple steps and massive

parallelization of similar techniques for high-throughput experimentation.

Stem cell research stands to gain from microfluidics in two fundamental ways:

• miniaturization of nearly all possible experimental techniques allows rapid

screening of phenotypic effects in cells

• various aspects of physics of the microscale allow many physiologically

relevant conditions to be achieved in an in vitro setting to create precise

microenvironment for stem cells


Using Lab-on-a-Chip Technologies Conclusions

The ability of microfluidics to precisely control the biochemico/mechanical and

physical microenvironment of cultured stem cells and automate observations and

analysis.


regenerative medicine and stem cells

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