RegenerativeTissue Matrix in

Treatmentof Wounds

Learning Objectives

• Differentiate between reparative and regenerative healing

• Review surgical techniques for applying a regenerative tissue scaffold to a variety of wound types

• Discuss the role of biologics in the continuum of wound care

• Review the evidence to support the use of acellular human dermal matrix for patients with chronic wounds

RegenerativeTissue Scaffolds:

Science andSurgical Applications

Regenerative Healing

• Regenerative vs reparative

• 80:20 rule

Regeneration of Connective Tissue Only Occurs at 2 Specific Times in Our Life Cycle

Noninflammatory process driven by

mesenchymal stem cells

Stem cellslocalize and divide

Normalstructure/function/physiology

Regeneration

Local signals instruct stem cellsto replace missing tissue

IntrinsicTissue

RegenerationProcess

The “Repair” Process Is Based on Inflammation and Leads to Scar Formation

Fibrin scaffold

Fibrosisand

remodeling to scar

Repair

Inflammationand

proliferation

Inflammation Is Important to Health

• Inflammation is initiated by activation of macrophages– Macrophage activation

– In-growth of white blood cells and other activated inflammatory cells

– Secrete collagen and ECM to replace the lost tissue with scar

– Inflammatory cells undergo apoptosis when the process is over

• Healing wounds (repair process)

• Fighting infection

• Protecting against foreign bodies

ECM = extracellular matrix.

Regeneration May Be Enabled Using Biologic Scaffolds

• Tissue contains the perfect scaffold for supporting the regenerative process

• Removing the scaffold from tissue without damage allows integration into the body

• Matrix damage triggers inflammation (and resorption or encapsulation)

Harper J, et al. Wounds. 2007;19(6):163-168.

Regenerative Tissue Scaffolds

Cellular Repopulation

Revascularization

Transition to Functional Host Tissue

The ECM Contains Complex 3-Dimensional Information

• Native collagen and key matrix components

• Matrix capable of supporting cell migration and capillary invasion (no abnormal cross-links)

• Rich in proteoglycans

• Initial biomechanics that support suture retention and high load

Harper J, et al. Wounds. 2007;19(6):163-168.

Fibrillar collagens and collagen VI

Hyaluronan

Large and smallProteoglycans

Fibronectin VascularChannels

Elastin

Regenerative Tissue Scaffolds

Internal Data from LifeCell, Inc.

Day 2

Day 14

Day 7

Day 21

Regenerative Tissue Scaffolds (continued)

Internal Data from LifeCell, Inc.

Regeneration of Normal Tissue

Human Tissue

Processing

RetainBiochemicalComponents

Family of ScaffoldsFamily of Scaffolds

GuidesRevascularization

& CellularRepopulation

PreserveIntactMatrix

Avoids Inflammatory

Response

RemoveCellular

Components

EliminatesImmune

Response

Animal Studies Have Shown That Acellular Regenerative Tissue Scaffolds Are Not Adhesiogenic*

Plast. Reconstr. Surg. 114:464, 2004

Plast. Reconstr. Surg. 125:167, 2010

*Correlation of these results to results in humans have not been established.Butler CE, et al. Plast Reconstr Surg. 2004;114(2):464-473. Burns NK, et al. Plast Reconstr Surg. 2010;125(1):167-176.

Cross-Linked Porcine ADM Is More Fibrogenic against Healthy Bowel than Noncross-Linked Dermal Matrix

ADM = acellular dermal matrix; PADM = porcine acellular dermal matrix. Butler CE, et al. J Am Coll Surg. 2010;211(3):368-76..

Cross-Linked PADM Noncross-Linked

Encapsulation(Cross-Linked Porcine Dermis)

Regeneration(Human RTM)

Resorption(Porcine Small Intestine SM)

RTM = regenerative tissue matrix; SM = submucosa. Sandor M, et al. Tissue Eng Part A. 2008;14(12):2021-2031.

Primate Abdominal Wall 4-Week Explants

Histology of Biologics in Primates

Histology of Biologic Explants in Primates

Sandor M, et al. Tissue Eng Part A. 2008;14(12):2021-2031.

Encapsulation(Cross-Linked Porcine Dermis)

Regeneration(Human RTM)

Resorption(Porcine Small Intestine SM)

Primate Abdominal Wall 6-Month Explants

100x

Cross-Linked Porcine Dermis WasInfected, Acellular, and Encapsulated

Courtesy of Dr. Patrick Osum, Little Rock, AR.

Human Abdominal Wall 3-Month Explant

Cross-Linked Porcine Dermis Has Been Shown Not to Integrate: Clinical Example

Courtesy of Dr. Terry L. Simpson, Phoenix, AZ.

Human Abdominal Wall 10-Month Explant

Biochemical Impairment of Chronic Wounds

• Elevated pro-inflammatory cytokines

• Elevated proteinase activity—MMPs

• Diminished activity of growth factors

• Degraded receptor sites (degradation blocked by the addition of MMP inhibitors)

MMP = matrix metalloproteinase.

Bacterial Biofilm Is a Major Barrier to Wound Healing

Comparison of Full-Thickness DFU Prospective, Randomized, Controlled Trials

Pivotal Study Study End Point

# of Applications

% of Wounds Healed

Average Time to Complete Healing

Reyzelman, et al 12 weeks 1 70% 5.7 weeks

Veves, et al 12 weeks 3.9 56% 9.3 weeks

Marston, et al 12 weeks 8 30% Not Reported

DFU = diabetic foot ulcer.Reyzelman A, et al. Int Wound J. 2009;6(3):196-208. Veves A, et al. Diabetes Care. 2001;24(2):290-295. Marston WA, et al. Diabetes Care. 2003; 26(6):1701-1705.

Clinical Effectiveness of an Acellular Dermal Regenerative Tissue Matrix Compared with Standard Wound Management in Healing

DFUs: A Prospective, Randomised, Multicenter Study

Patients in Study N = 86 Study Group = 47

Received a single application of4X4 cm human acellular regenerative tissue matrix

Control = 39 Received standard-of-care wound management

consisting of moist wound therapy withalginates, foams, hydrocolloids, or hydrogels.

Primary End Point:Proportion of ulcers that completely healed at 12 weeks

(complete healing defined as 100% epithelialization)Secondary End Point:Mean time to healing

Reyzelman A, et al. Int J Wound. 2009;6(3):196-208.SD = standard deviation.Reyzelman A, et al. Int J Wound. 2009;6(3):196-208.

Clinical Effectiveness of an Acellular Dermal Regenerative Tissue Matrix Compared to Standard Wound Management in Healing

DFUs: A Prospective, Randomised, Multicenter Study

• Mean age: 55-59 years

• Majority were patients with type 2 diabetes

• Obese

Demographic Variable Study Group(n=46)

Control Group (n-39)

Age (years)Mean MedianSDRangeNumber of patients

55.455.09.6

32-7846

58.958.011.6

35-9339

Body mass index (lbs/in²)Mean MedianSDRangeNumber of patients

33.132.16.7

24.3-52.845

34.633.58.5

20.9-61.138

Diabetes mellitus typeType 1Type 2Number of patients

5 (10.9%)41 (89.1%)

46

2 (5.1%)37 (94.9%)

39

Most Common Ulcer Area: Foot

Comparison of Index Ulcer Locationbetween Treatment Groups

Pretreatment Ulcer Duration(weeks)

StudyGroup(n=46)

ControlGroup(n=39)

Mean 23.3 22.9

Median 16.0 12.0

Standard Deviation 22.4 29.8

Range 0.00-96.00 3.00-139.00

Mean PretreatmentUlcer Duration:

~23 Weeks

Reyzelman A, et al. Int J Wound. 2009;6(3):196-208.

Demographics

0

5

10

15

20

Foot Heel

Wound LocationToe Other

Num

ber o

f Pat

ient

s Moist WoundTherapy

Acellular Matrix32.6%

12.8%

32.6%

43.6%

8.7%

20.5%

10.9%

7.7%

Surgical Preparation of Wound Site Followed by Randomization into 1 of 2 Groups

Study Group (n = 47)• Single application of acellular

dermal regenerative matrix for wounds (fenestrated) scaffold RTM 4x4 applied

• Secured via suture or staple

• Silver-based nonadherent dressing applied

• Secondary dressings (hydrogel bolsters or moist gauze) were applied routinely at the rate determined by the investigator until complete epithelialization was achieved or 12 weeks of care

Control Group (n = 39)• Received standard of wound care

• Moist wound therapy with alginates, foams, hydrocolloids or hydrogels at discretion of treating physician

• Alginates with foam typically used for heavily exudative wounds

• Hydrocolloids or hydrogels typically used for minimal exudating wounds

• Dressing changed daily unless recommended otherwise by treating physician

Reyzelman A, et al. Int J Wound. 2009;6(3):196-208.

Survivorship Analysis toComplete Healing

AM = acellular matrix; SOC = standard of care; CI = confidence interval.Reyzelman A, et al. Int J Wound. 2009;6(3):196-208.

0

0.2

0.4

0.6

1.0

0 2 5 10 12

Time to Healing (weeks)1 3 7 119

Surv

ival

Pro

babi

lity 0.8

64 8

Standard of care

AM

P = .0075

Product Limit Survival Function Estimates

70% of AM patientshealed by 12 weeks

46% of standard of care patients healed by 12 weeks

+++

+

+

+ ++

+

++

ACM

SOC

No. of Subjects Event Censored Median Survival (95% CI)

AM 46 70% (32) 30% (14) 7.00 (4.00-11.00)

Standard of care 39 46% (18) 54% (21) 12.00 (9.00-NA)*Proportion of patients who completely healed as defined as 100% epithelialization.Reyzelman A, et al. Int J Wound. 2009;6(3):196-208.

Proportion of Healed Ulcers atWeekly Evaluation Intervals

0

0.1

0.2

0.4

0.6

0.8

0 2 5 10 12

Time to Healing (weeks)1 3 7 119

Hea

ling

Prop

ortio

n*

0.3

0.5

0.7

64 8

Moist Wound Therapy

AM Therapy

15% Highervs

Control

AM

SOC

P = .0289

AM group = 5.7 weeks

Control group = 6.8 weeks

Proportion of healed ulcers between groups was statistically significant

Patients that Completely Healed the Mean Time to Complete Healing

Summary

• Efficacy for AM demonstrated in UT Grade 1 and 2 diabetic foot ulcers

• 70% of AM patients completely healed

• Healed patients reached 100% epithelialization in 5.7 weeks (mean closure)

• Human acellular regenerative tissue scaffolds provide an effective treatment option for diabetic lower extremity wounds in a single application

UT = University of Texas Classification System.Reyzelman A, Crews RT, Moore JC, et al. Int Wound J. 2009;6:196-208.

Conclusion

• The AM is a viable treatment option for the treatment of lower extremity diabetic wounds

• A multicenter prospective study is underway to further validate the safety and efficacy of the AM

Results from 97 Wounds

• 97 Wounds from 71 patients

• 33 females (46.5%)

• 38 males (53.5%)

• Mean age 62.2 (40.0-85.9)

• Mean wound age is 18.6 weeks

Winters CL, et al. Adv Skin Wound Care. 2008;21(8):375-381.

1B = 11C = 01D = 2

2B = 8

2C = 42D = 3

3B = 7

3C = 3

3A = 3

UT Classification

1A = 15

3D = 33

2A = 18

Patient Comorbidities

Neuropathy

Cardiac Disease

Peripheral Vascular Disease

Infection

Obesity

Osteomyelitis

0 20 60 70 100

Percent Population (%)10 30 40 908050

87.6%

86.8%

81.4%

54.6%

52.0%

37.1%

Results*

• No significant difference between time to graft incorporation, time to 100% granulation, and time to complete healing and UT classification

*Complete healing defined as full epithelialization.Winters CL, et al. Adv Skin Wound Care. 2008;21(8):375-381.

StudyPopulation

(n=97)

UTGrade 1(n=18)

UTGrade 3(n=33)

UTGrade 3(n=46)

Time to Graft Incorporation (weeks)Mean ± SDMedianRange

1.5 ± 0.901.3

0.43 − 4.4

1.5 ± 0.552.0

0.71 − 2.0

1.6 ± 0.901.3

0.57 − 3.0

1.5 ± 1.01.1

0.43 − 4.4

Time to Graft Incorporation (weeks)Mean ± SDMedianRange

5.0 ± 3.54.0

0.43 − 16.7

4.4 ± 2.14.0

1.4 − 8.0

5.3 ± 3.84.0

0.71 − 16.7

5.1 ± 3.83.6

0.43 − 14.9

Time to Graft Incorporation (weeks)Mean ± SDMedianRange

13.7 ± 9.010.9

1.7 − 57.6

10.8 ± 3.29.5

5.0 − 17.0

12.3 ± 7.010.0

1.7 − 29.7

16.4 ± 11.513.9

4.7 − 57.6

Results

• Overall graft success rate was 89.7%

• 1 graft failure-healed 7 weeks post 2nd application

• Overall wound closure rate was 90.7% (88 of 97)

• Mean time to heal was 13.7 weeks

Complete healing defined as full epithelialization.Winters C, et al. ASWC. 2008;21:375-81.

Wounds Healedwith Single Graft

Application

OverallHealing Rate

Did Not Heal 9.3%Did Not Heal 9.3%Multiple

Graft ApplicationsRequired 1%

90.7% 89.7%

AcellularHuman Dermal Matrix

forChronic Wounds

Surgical Technique Surgical Technique (continued)

Case 1: 58-Year-Old Female with Submetatarsal Wound Present for 1 Month Case 1: Matrix and NPWT

NPWT = negative pressure wound therapy.

7 Days Postop

Case 1: Matrix and NPWT Therapy (continued)

15 Days Postop

Case 1: Matrix and NPWT Therapy (continued)

42 Days Postop

Postoperative ScenariosCase 2: 54-Year-Old Male with Full Thickness

Wound on Medial Ankle, Exposed Tibia,Noninsulin Dependent Diabetic

Case 2: 5 Days Case 2: 3 Weeks

Case 2: 4 Weeks Case 2: 6 Weeks

Case 3: 37-Year-Old Male with OpenTraumatic Amputation with Loss of Lesser Digits

and Distal MetatarsalsCase 3: Preservation of Distal Tissue

Use of ADM to preserve distal tissue for function and patient request

Case 3: 2 Weeks Post-Applicationof ADM

Case 3: 7 Weeks Post-Applicationof ADM

Flowable Dermal Scaffold

• Micronized dermal scaffold

• Same physiologic properties without intact vascular channels

• Use in tunneling wounds

Surgical Technique

Tunneling Wounds? Postoperative Appearance

7 Days Postop

Case 4: 87-Year-Old Diabetic Female with Multiple Failed Debridements Case 4: Intraoperative Photo

Case 4: Scaffold Placement Case 4: Flowable Scaffold

Case 4: 5 Days Post-Application Case 4: 13 Days Post Flowable Application Laterally

Case 4: 20 Days Post-Application Case 4: 42 Days Post Flowable Laterally

Case 4: 42 Days Post-Application (patient transferred to another facility)

Thank You