Manifestation of Novel Social Challenges of the European Union in the Teaching Material of Medical Biotechnology Master’s Programmes at the University of Pécs and at the University of Debrecen

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at the University of Pécs and at the University of Debrecen

Identification number: TÁMOP-4.1.2-08/1/A-2009-0011

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COMMERCIAL PRODUCTS (1)

Dr. Judit Pongrácz

Three dimensional tissue cultures and tissue engineering – Lecture 21

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Organ failure

Organ failure is organ dysfunction to such a degree that normal homeostasis cannot be maintained

without external clinical intervention.

• Recently, a curative therapy for organ failures is only organ transplantation

• Regenerative medicine offers the solution to avoid graft rejection, the most common complication of transplantation

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Regenerative medicine

Regenerative medicine is the process of creating

living, functional tissues to repair or replace tissue or organ function lost due to damage, or congenital

defects.

It has the potential to solve the problems of:

• the shortage of organs available for donation

compared to the number of patients that require life-saving organ transplantation

• organ transplant rejection, since the organ's cells will match that of the patient

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engineering

• Rapid development of tissue engineering allows the commercialization of several products

• Cellular therapies offer therapeutic solutions for serious diseases like organ failure

• More and more products are approved for regular clinical use

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Cardiovascular diseases

Aortic valve

Tricuspid valve

Bicuspid valve Pulmonary valve

Right coronary artery

Left coronary artery

Heart valves

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Artificial heart valves

• Mechanical heart valves are made of biocompatible metal alloys and plastics

• Durable structure, may last for many years

• The non-biological surface of implants may cause blood clotting disturbances

• Bacterial infection is a serious risk

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Biological heart valves

• Valves of animals, like pigs, which undergo a

decellularization procedure in order to make them suitable for implantation in the human heart.

• Other types of biological valves (made from

decellularized equine or bovine pericardium) are sewn to a frame

• They are less durable than mechanical valves

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Tissue engineered heart valves

Scaffolds seeded with endothelial cells Perspective:

• Enhanced durability

• No clotting disorders

• No increased infection risk

• Similar mechanical properties to that of native valves

• BMMC seeded TE heart valves are available but only for the pulmonary circulation (right heart

side)

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Replacement of blood vessels

• Arterial „organ failure” occurs mainly as a result of atherosclerosis

• Venous „organ failure” occurs most frequently in venous varicosity

• Replacement of damaged organs: only arteries

• Autografts, xenografts, artificial stents or blood vessels

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Vascular tissue engineering

• Xenografts: decellularized veins, ureters or intestinal submucosa from animals (canine, porcine, rabbit origin mainly)

• Recently, human allografts are used also

• PCLA-PGA copolymer heart valve constructs seeded with BMSC in paediatric patients

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Developments in vascular TE

Tissue printing of a blood vessel:

• Cells: mixture of

smooth muscle and endothelium

• Spontaneous structure will form

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Vascular grafts

• Vascular grafting in surgery uses mainly autografts:

the patient’s own veins or arteries are used to bridge closures on blood vessels.

• Example: CABG surgery

• Vascular stenting: Percutaneous Coronary

Intervention (PCI), Abdominal Aortic Aneurysm treatment

• Artificial blood vessel: Aortofemoral bypass

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Vascular tissue engineering

• Xenografts: decellularized veins, ureters or intestinal submucosa from animals (canine, porcine, rabbit origin mainly)

• Recently, human allografts are used also

• PCLA-PGA copolymer heart valve constructs seeded with BMSC in paediatric patients

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Tissue engineered blood vessel

• TE blood vessels are used only in low pressure pulmonary circulation

• These grafts are not durable enough to withstand high arterial pressure

Small-vein harvest

Cell seeding on polymer Cell isolation

Cell expansion

Tissue-engineered graft

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TEBV production

• HUVEC and SMC were grown in conventional tissue culture flasks to form a monolayer which could be peeled off

• Monolayers were wrapped around inert tubular supports to form concentric layers

• Inner membrane: dehydrated fibroblast sheet

• Smooth muscle cells formed the second sheet

• Fibroblast sheet was rolled on to form an adventitia

• Endothelial cells were seeded on the inner surface

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Cartilage injury and regeneration

• Cartilage injury: acute or chronic

• Acute injury: mainly traumatic

• Chronic injury: inflammation/degeneration

• Arthritis/Arthrosis

• Regeneration is slow and in case of massive

damage or chronic disease, degeneration occurs

• Heavily effects life quality and frequently occurs in the developed world

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Challenges for cartilage TE

• Hyalinous cartilage, not fibrous cartilage needed

• Avascular tissue, chondrocytes have low metabolic rate

• Mechanical stimulation of engineered construct is necessary for good results

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(ACI) I

• 200-300 mg cartilage is harvested by

arthroscopically from a less weight bearing area (intercondylar notch superior ridge of the medial or lateral femoral condyle)

• The matrix is digested enzymatically, chondrocytes are isolated

• Chondrocytes are cultured in vitro for approximately four to six weeks

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(ACI) II

• Cultured chondrocytes are applied on the damaged area during an open-knee surgery (also called

arthrotomy). These autologous cells should adapt themselves to their new environment by forming new cartilage.

• During the implantation, chondrocytes are applied on the damaged area in combination with a

membrane (tibial periosteum or biomembrane) or pre-seeded in a scaffold matrix.

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(ACI) III

Biopsy of healthy cartilage

Cultured chondrocytes injected under patch

Periosteal patch harvested from tibia Damaged cartilage

(Lesion)

Tissue culture of isolated chondrocytes

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Commercial products for ACI

• Carticel® service: Genzyme

• Harvested cartilage is sent to Genzyme

• Release of chondrocytes, culturing and proliferation of chondrocytes are performed by the firm

• The surgeon receives the ready-to-implant differentiated cells

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Matrix-induced ACI (MACI)

• Harvested chondrocytes are expanded on hyalin or collagen matrices

• No significant difference in the clinical outcome between ACI and MACI

• Use of MSCs in MACI are in trial currently

• Main challenge: differentiation towards hyalin cartilage instead of fibrous cartilage

• Many different matrices are used

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COMMERCIAL PRODUCTS (2)

Dr. Judit Pongrácz

Three dimensional tissue cultures and tissue engineering – Lecture 22

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Bioartificial liver Assist Device

• Liver has remarkable regeneration capacity on its own

• Liver replacement treatments are applied in both acute and chronic liver failure

• Bridges the time until a suitable donor is found

• Support until the transplanted liver starts working

• Treatment option for acute-on-chronic liver failure

• Treatment in acute liver failure: replacing liver

detoxification function until the patient’s own liver regenerated on its own

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Liver dialysis

• Dialysis-like solutions

• No living cells used

• Ammonia causes encephalopathia

• Extracorporeal detoxification

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Bioartificial liver

Patient’s plasma

Oxygen

PKM-19 Liver cells Plasma

filter

Bioreactor

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ELAD bioartificial liver

Blood circuit

Ultrafiltrate circuit Glucose

ELAD^TM

ELAD^TM ELAD^TM ELAD^TM

Plasma filter

Oxygenator

Pumping system

Reservoir

Blood pump

Ultrafiltrate pump

Recirculation pump

Glucose infusion pump Priming

infusion line

Heparin infusion

Incubator

Cell filter

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Cell-free ELAD: MARS

MarsFlux Dialyzer diaMarsFlux Adsorption columns

diaFlux Dialyzer Blood circuit Mars-Albumin circuit Dialysate circuit

Blood pump

Albumin pump Activated

charcoal Anion

exchange resin

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Skin grafting and replacement

• Burn injuries

• Chronic wounds, e.g. diabetic or PAD ulcers

• Cosmetic surgery

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Structure of the skin

Epidermis

Dermis

Fat

Sweat gland

Erector pili muscle Hair

Sebaceous gland

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Purpose of skin grafting

• Restore the barrier function → keratinocytes

• Recently no nerve, vascular, sweat glands or hair follicles can be included into the skin

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Split-thickness grafts

• Full thickness burns → dermis AND epidermis are both lost

• Partial thickness burns → epidermis is largely intact

• If more, than 30-40% body surface is burnt, TE products are welcome by surgeons

• Smaller surface burns may be cured with split thickness autografts

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Autologous skin grafts

Skin is meshed to cover a large wound

Graft taken from patient’s healthy skin

Wound

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Integra skin replacement

1. A patch of synthetic skin is placed on top of damaged tissue

Undamaged dermis

Silicone membrane

Undamaged epidermis

Underlying tissue

Synthetic skin patch with silicone membrane

Blood vessels forming

3. The blood vessels restart blood flow to the area and the silicone membrane

is removed 2. The patch contains chemicals that

trigger growth of new blood vessels and proteins for skin regeneration

7 days after application 14+ days after application

4. A small graft of the patient’s own skin replaces the silicone membrane

Meshed skin graft

14+ days after application

5. The skin graft eventually creates a smooth surface of regenerated skin

Regenerate d skin

35+ days after application

Restarted blood flow

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Cultured Epithelial Allograft (CEA)

• CEA alone

• Integra combined with CEA