2011-08-11

1

New Frontiers and Future Technologies:

Biomaterials, Stem Cells and Tissue Engineering

W. John Kao PhD

Professor of Biomedical Engineering, Pharmacy, and Surgery

University of Wisconsin – Madison

wjkao@wisc.edu

John.Kao.Lab

New Frontiers (challenges) and Future Technologies:

Biomaterials, Stem Cells and Tissue Engineering

Acknowledgments: those who kept us going!

My Students:K Kleinbeck, H Waldeck, Y Fu, C Drifka, K Xu, D Cantu, J Li, A Chung, D Schmidt, S Zuckerman, H Yang, Y Gao, J Phillips, J Meyers, E Joyce, W Johnson, H Cohen

Physician Collaborators: J Niezgoda, L Faucher, M Schurr, P Hematti, H Summer, J Farinas

Basic Science Collaborators:L Allen-Hoffman, G Kwon

Wisconsin Alumni Research Association (WARF): L Cagan, J Burmania, C Gunbrandson

Funding AgenciesNIH, NSF, UWF, UW BME, UW Surgery, UW Pharmacy, WARF, MatriLab

2011-08-11

2

Outline for this talk

Introduction to clinical challenges

Advanced wound healing therapy: basic research

> Biomaterial-enabled tissue engineering strategies

> Cell-based therapy + HBO2T strategies

What’s next? Going beyond basic research in academia

Introduction to Clinical Challenges

Clinical needs:acute and chronic cutaneous wound healing

Cost of trauma-related deaths in US is 2.4X higher than cancer and cardiovascular diseases combined. *

By 2020, trauma will equal or surpass communicable diseases as the number one cause of disability-adjusted life years worldwide. *

Greater than 50% of wounds remain refractory to current conventional treatment. *

Outcome of acute and chronic cutaneous wound healing can’t be reliably predicted.

* http://www.cdc.gov/ncipc/wisqars/

2011-08-11

3

The choice of treatment and the development of novel therapeutics depend on the underlying biology and co-morbidity.

Current understanding of many cellular and molecular processes has advanced substantially.

However, efficacy of biomolecules as single agent therapeutics is disappointing.

Complex biochemical pathway

Dynamic wound healing cascade

Underlying pathology

Challenges

Challenges: complex biochemical pathways

Altered genes (+ 5000) in a neutrophil when exposed to LPS

from Calvano SE et al. A netowrk based analysis of systemic inflammation in human, Nature. 2005; 437, 13, 1032.

Challenges: dynamic wound healing cascade

Hemostasis: fibrin clot, platelet aggregation

Inflammation: exudation, phagocytosis, cytokine/growth factor release

Granulation/proliferation: fibroblast/endothelial cells, angiogenesis, provisional matrix formation, wound contracture

Time

Remodeling / Re-epithelialization:Resorption of type III collagen,Type I collagen formation and fiber orientation, keratinocyte proliferation and epithelialization

Chronic or impaired wounds result when tissues fail to progress through

these stages of healing !!

2011-08-11

4

Advanced Wound Healing Therapy

Biomaterial-enabled tissue engineering strategies:biomimetic biomaterials

New therapeutic paradigm:using biomaterials and therapeutic cells to recapitulate the lost tissue structure and to address underlying disease to improve healing.

Adapted from Clark et al.J Invest Derm 2007

Ideal biomaterial properties

Well-characterized

Biocompatible, safe and effective:

Adheres to tissue and conforms to complex contour

Maintains moist healing environment

Functionalizable to promote healing and patient care

IP protected

Cost effective to synthesize and manufacture

Easily adaptable to current clinical practice

Easy patient compliance

2011-08-11

5

Examples of clinical biomaterial-based treatment (for granulation wounds)

foams, hydrogels, transparent films, hydrocolloidsprovide a moist environment, some insulation

Allevyn®, Curafoam®, Curasol Gel®, Biolex Wound Gel®,

Bioclusive®, Tegaderm®, DuoDerm®, Replicare®

Adjunctive Therapies: NPT, acellularized tissue graftsVAC®, Oasis®

Although all meets some aspects of “ideal” biomaterials,there remains room for improvementproduct differentiation

labor-intensive patient care

needs to address co-morbidity and underlying pathology

unclear mechanism theory: why and how it works

ScaffoldsPEGdA-PEGSH :chemically modified gelatin

To study cell-material interaction To promote cell integration and tissue

regenerationTo study material structure-function.

Present actives:Therapeutic cells, peptides, proteins, analgesics, antimicrobials, immunocytokines as soluble or immobilized PEGylated molecules

To influence cell-material interaction,To enhance clinical utility.

Extracellular matrix (ECM) – mimics semi-interpenetrating networks (sIPN)

FODay 0

Day 21

sIPN-mediated wound healing in full thickness defects

Waldeck H, Kao WJ. J Biomaed Mat Res (2007), 82A, 861-871

sIPN with soluble KGF and grafted RGD(day 21)

sIPN w/o loaded biomolecules(day 21)

Conventional cotton dressing with Ag (day 21)

2011-08-11

6

sIPN-mediated wound healing in partial defects

Acticoat™ graft Tisseel/Telfa graft IPN graft Xeroform

3 weeks later:

sIPN promotes healing by modulating monocyte, fibroblast, keratinocyte paracrine regulation

This image cannot currently be displayed.

Expanding sIPN clinical utility as a drug delivery matrixpharmaceuticals: AgSD, Bupivacaine to manage co-morbidity

• released silver sulfadiazine maintained bioactivity in bacteria kill efficiency

S. Aureusfreshly plated ----confluent ––

methicillin resistant S. aureusfreshly plated ----confluent ––

P. aeruginosafreshly plated ----confluent ––

Drug loaded sIPN

Area of bacterial kill

2011-08-11

7

L-WBG

No WBGS-WBG

M-WBG

Expanding sIPN clinical utility as a drug delivery matrixpharmaceuticals: WBG® reactive oxygen species scavenger

PMNs

Chamber A

Chamber B

OxyBurst H2HFF-BSA+

PMA

Extracellular ROSprobe

Stimulates ROS production by PMNs

0

5

10

15

20

L-WBG M-WBG S-WBG No WBG

Equ

ival

ent

fluor

esce

in M

FI (

nM)

a decrease in detected ROS with the addition of L-WBG

Chamber AChamber B

Advanced Wound Healing Therapy

Cell-based therapy strategies

New therapeutic paradigm:using biomaterials and therapeutic cells to recapitulate the lost tissue structure and to address underlying disease to improve healing.

Adapted from Clark et al.J Invest Derm 2007

2011-08-11

8

Epidermal, dermal, epidermal/dermal equivalents

Epidermal constructs (permanent transplant):

Autologous keratinocytes on various substrates

CellSpray®, Epicel®, Epidex®, EPIBASE®, MySkin®

Dermal constructs (permanent to temporary usages):

Decellularized ECM, neonatal allogeneic fibroblasts oncollagen

Alloderm®, SureDerm®, Matriderm®, OASIS®, EZ Derm®

Transcyte®, Dermagraft®, Hyalograft®

Epidermal/dermal equivalents (temporary applications):

Allogeneic keratinocytes/fibroblasts on collagen

Apligraft®, Orcel®, PolyActive®

Primary mode of action is to deliver cell-derived factors

Room for improvement

Epidermal constructs (permanent transplant):+3 weeks waiting period for autologous cells to expand

Not effective in full thickness wounds or acute care

Cost

Dermal constructs (permanent to temporary usages):Compositionally complex ECM

Although immune tolerant, allogeneic fibroblasts undergofunctional changes during established entrapment methodsand storage

Requires second procedure for removal

Epidermal/dermal equivalents (temporary applications):+4 weeks of complex, labor-intensive manufacturing process

Cost

Requires second procedure for removal

Entrap therapeutic cells within sIPNfacile, in situ forming, organogenetic epidermal/dermal equivalent to deliver cell-derived healing promoting factors to the wound bed

PEG-dithiolPEGdA

Mix

+ +

Therapeutic cells in suspension

Cell encapsulated sIPN matrix

Gelatin

Gelatin modified with biofunctional peptides

2011-08-11

9

Feasibilityin-gel cells maintained viability +14 days in vitroin vivo in situ gel formation post subcutaneous injectionmaterial-modulated keratinocyte-fibroblast interaction

viability

active cell-materialinteraction

activecytoskeletalformation

In vivo tissue-sIPN interface post sub-q injection

modulation ofprotein release

Promising therapeutic cells to be delivered via sIPN

Allogeneic human dermal fibroblasts/keratinocytesclinical experience

Mesenchymal stem(stromal) cells (MSC)easily accessible, multiple tissue sources

positive for mesodermal lineage markers CD29, CD44, CD90

negative for hematopoietic marker CD14upon proper stimuli, differentiable to various lineages

immune tolerant and inflammatory modulatory

Human epithelial progenitor cells (NIKS®)genetically identical, proliferative

undergo normal epidermal differentiation

long-lived phenotype enables stable transfection

Allogeneic BM-MSC injected into partial thickness wounds dressed with: Acticoat, Tisseel, Autograft, sIPN in pigs

MSC improved macroscopic wound healing (VSS: vascualrity,pigmentation, pliability and height),

However, delivered MSC only lasted up to 7 days in vivo.

sIPN with MSCMSC Tissue MSC MSC + sIPN

in 7 d in 7d

2011-08-11

10

The role of hyperbaric oxygen therapies (HBO2T):Increased native circulating MSC mobilization and wound recruitment in diabetic patients *

* Thom SR et al. Wound Rep Regen. 2011, 19, 149-161.

Circ endothelialProgen cells

Lower extremity wound margin with HIS for HIF-1,endothelial progenetor cell markers CD34, CD133after 3 wk of HBO2T

HBO2T increased:

circulating endothelial progenetor cells (L)

and

platelet NOS activity (R)in

diabetic patients undergoing treatments

vs. healthy patients

NIKS®genetically modified to overexpress VEGFpromote HuMVEC proliferation in vitroseeded onto gelatin, cultured, transplanted into full-thickness wounds in

db/db diabetic mice resulted in improved healing

Future challenges for biomaterial-enabled cell-based advanced wound therapies

Difficult to harmonize various pre-clinical & clinical resultsMultiple delivery matrices

(hyalluronic acid, alginate, chitosan, fibrin, synthetic hydrogels)

Multiple cell sources and manipulation methods(autografts vs allografts vs xenografts)

Multiple methods of cell introduction(timing as a function of wound progression, injection vs implant)

Incomplete understanding of the mode of action(engraftment vs paracrine regulation)

Commercializationscale-up, manufacturing, batch consistency, regulatory pathway,

cost, competitiveness over other methods of care

2011-08-11

11

What’s Next?

Going beyond basic science research in academia

Traditional role of university in translational research:idea generation, patent prosecution, licensing

Idea or invention

Research Prototyping

Manufacturing

Initial clinical safety testing

Clinical trials Commercialization

Regulatory (FDA) review

Patent application

US Patent Office review Traditional licensing window

Patent issued

Highestcommercial risk

Lowestcommercial risk

traditional role of university

Problems with the old model:

Investors and industry increased cost sensitivity and risk aversion.

Lack of commercial pathways for numerous issued patents held by universities.

Too few promising drugs and devices in development pipeline to tackle current clinical needs.

Formation of National Center for Advancing Translational Sciences at the National Institutes of Health (US).

Mission: to “de-risk” promising technologies so they are attractive to potential licensers for product development commercialization.

2011-08-11

12

Paradigm Shift:the role of university in “de-risking” a technology

Idea or invention

Research Prototyping

Manufacturing

Initial clinicalsafety testing

Clinical trials Commercialization

Regulatory (FDA) review

Patent application

US Patent Office review Traditional licensing window

Patent issued

Current licensing window

traditional role of university

PARADIGM SHIFT: redefined role of university ?

Highestcommercial risk

Lowest commercial risk

“de-risking” = “value-added”

Roadmap for FIM study: a collaborative effort

1. Establish manufacturing process for sIPN base formulation

2. “product” validation and verification

3. Complete a first-in-human safety trial in a controlled and clinically relevant model: skin donor graft site wounds in traumatic acute wound patients

4. Later project may address sIPN in other types of wound and/or to present actives.

Key Benchmarks: unfamiliar territory for academia

• Develop packaging system and methods

• Determine sterilization methods

• Develop manufacturing processes

• Design Verification and Validation testing

• Complete additional animal studies (if needed)

• Complete Biocompatibility tests

• Develop first-in-man (FIM) Protocol

• Approval from governing body for clinical human use

2011-08-11

13

Challenges for technology translation in academia

• Alignment with institutional missions and priorities.

• Ability to predict market needs

• Ability to select and to develop commercialization pathways for numerous issued and filed patents in the portfolio.

• Lack of quality systems and know-how’s in “product” development to “de-risk” promising technologies in medical devices, drugs or combination products.

• Lack of human resources and capitals to pursuit business ventures.

General Conclusions:

Wound healing remains a pressing clinical challenge.

Innovation and interdisciplinary approaches are absolutely essential to develop advanced wound therapies.

Biomaterial-enabled, cell-based approaches coupled with existing practices such as HBO2T are promising in improving current therapies, patient management, and healing outcome.

Technology translation pathways and know-how’s from academia to industry remain a challenge to fully realize

the clinical impact of promising technologies.

Thank You !W. John Kao

wjkao@wisc.edu