Module 8 Flashcards
In aesthetic surgery, give examples of the use of regenerative and stem cell based therapies.
Lipofilling Stromal regenerative cells Expanded stem cells Collagen induction agents Platelet growth factors' rich products
Define regenerative medicine.
RM seeks to devise new therapies for patients with severe injuries or chronic diseases in which the body’s own responses do not suffice to restore functional tissue.
RM introduces novel methods and strategies to replace or regenerate cells, tissues or organs in order to restore and establish normal function.
REPAIR or REPLACE
What strategies are used in regenerative medicine?
Cell-based therapies
Biomaterials
Scaffolds seeded with cells
New: nano-medicine, tissue engineering, rehabilitation sciences + social/ethical/environmental/legal issues
What types of cells have been used in transplantation?
Autologous or allogenic mature functional cells (cell replacement)
Modified human cells (cell based gene therapy)
Stem cells
Describe scaffolds.
Basic tool for cell transplantation
Made by natural or synthetic materials with diverse bioactivity and mechanical strength
Provides appropriate environment for cellular growth and organogenesis
Describe tissue regeneration.
Repair of damaged tissues and cells via cell/tissue transplantation, excluding organ transplants
Tissue engineering achieves this by combining materials design and engineering with cell therapy
Describe biomaterials.
Provides physical support for engineered tissues and powerful topographical and chemical cues to guide cells
Involves synthesis, processing and characterisation of novel materials, including polymers, proteins, glasses, cements, composites and hybrids
What are the two categories of cell-based therapies?
- Cells for structural repair or replacement (e.g. cultured dermal fibroblasts for skin replacement, chondrocytes for cartilage replacement)
- Cells for correction of a physiological or metabolic problem - autologous vs allogenic
What are stem cells?
Cells with the ability to:
- self-renew, perhaps indefinitely
- propagate without becoming malignant or aneuploidy
Define totipotent
Able to produce any cell type including the germ line e.g. fertilised oocyte
Define pluripotent
Able to give rise to many cell types of main 3 germ layers e.g. early embryonic stem cells
Define multipotent
Gives rise to a limited number of cell types e.g. bone marrow stem cells
Define unipotent
Gives rise to a single cell type e.g. skin stem cells
What are the 2 origins of stem cells?
- Embryonic stem cells
2. Adult stem cells
What are the 4 essential features of embryonic stem cells?
- Capacity to self-renew, perhaps indefinitely, without change of their genotype or phenotype
- Pluripotent (or even totipotent): have the potential to differentiate into any somatic cell lineage, including derivatives of all 3 germ layers
- Can contribute to every tissue type including germ line
- Able to form teratocarinomas (undifferentiated malignant tumours composed of tissues resembling derivatives of all 3 germ layers) when introduced into adult tissue
What factors maintain pluripotency of ES cells?
Cytokine leukaemia inhibitory factor (LIF)
Intracellular proteins - p21 and p53
What are iPS cells?
Recently discovered that transfection of 4 transcription factors Sox2, Klf4, Myc and Oct3/4 is sufficient to cause somatic, differentiated cells to re-enter the cell cycle and become pluripotent
What are mesenchymal stem cells?
Non-haematopoeitic stem cells found in bone marrow that constitute part of the stroma cell population.
- Plastic adherence in cell culture
- Specific surface antigen expression
- Multi-lineage differentiation in vitro
Easily cultured with high rate amplification at short term
Exert paracrine effect - enhance ability of tissue to repair itself
What are adipose-derived stromal vascular fraction?
A collection of heterogenous cells most notably stromal cells, endothelial and endothelial progenitor cells, haematopoietic cells and pericytes
What are adipose-derived stromal cells?
Multipotent cells - adipocytes, osteoblasts, chondroblasts, other mesodermic lineages
Derived from stromal counterpart of AD-SVF
Examples of autologous cell products
Epicel - permanent skin replacement product
Carticel - chondrocyte based treatment
Disadvantages of autologous vs allogenic
Autologous:
- bespoke, limited issues with tolerance
- limited by type of tissue, condition of tissue and patient factors, such as age, condition
- scheduling requirements for industrial scale manufacturing
Allogenic:
- easier in use, time and cost effective
- on demand
- immunosuppression may be required
Examples of allogenic cell products
Dermagraft and Apligraft - expanded cells from foreskin of donors. Minimal immune rejection.
Define cell-based therapies
- The administration of living cells, other than transfused blood products to humans for therapeutic or preventative purposes
- The cells are ex-vivo manipulated (selected, expanded, modified etc) to achieve their intended medicinal function
- May be delivered in many ways - infusion, injection, surgical implantation, aggregated with biomaterials or medicinal device
How does differentiation level affect cell therapy?
Differentiated functional cells:
- Drug cells behaving as in vivo sources of molecular species needed by the recipient (insulin supplied by allogenic pancreatic cells)
- Adoptive immunotherapy (cells to target cancer cells/infection)
Stem/progenitor cells:
- Long term substitution of injured cells
What does ECM consist of?
- Structural proteins (collagen, fibrillins, elastin)
- Specialised proteins (fibronectin, laminins, integrins)
- Proteoglycans (composed of protein core to which is attached long chains of repeating disaccharide units termed of glycoaminoglycans)
What is epithelial to mesenchymal transition?
The process by which the epithelium generates mesenchymal stem cells
e.g. mesoderm formation from epiblasts, delimitation of neural crest cells from the neural tube, invasion of endothelial cells intro cardiac region, in adults wound healing, metastatic cancers
What are the components of the cell microenvironment that have an affect on the behaviour of cells?
- ECM
- surrounding cells
- cytokines, GFs, hormones and other bioactive agents around the cell that are secreted by autocrine, paracrine and endocrine mechanisms
- Nano/microscale orientation and physical properties of adjuvant cells and the ECM
- Mechanical forces caused by the organism itself or movement of bodily fluids such as blood
Microenvironment controls plasticity, proliferation, differentiation and apoptosis
What are some ethical considerations in the use of stem cells?
- Where are cells coming from? How is it harvested? - use of embryos and cadaveric fetuses
- Affordability and accessibility
- Research is costly and time-consuming
- Patients may continue bad lifestyle habits and behaviours as RM can cure diseases
- Caring for an ageing population if RM helps people to live longer
Describe the ageing process.
- Bone resorption and remodelling - consequences for positioning and support of soft tissue overlap
- Fat compartments volume loss and redistribution - deep fat compartments decrease and superficial fat compartments increase
- Muscle atrophy - with age, muscles straighten and shorten due to reduction and redistribution of deep fat compartment. Muscle action is in more contractive state. Loss of muscle size and strength.
- Collagen loss - along with reduced elastin and hyaluronic acid, leading to loss of dermal support.
What is the mechanism of action of PLLA?
PLLA is a synthetic polymer that is both biocompatible and biodegradable. When constituted with sterile water for injection, it is injected deep into SC tissues or on the periosteum where it stimulates fibroblasts to produce new collagen.
What are the contraindications of PLLA?
Hx of autoimmune disease
Keloid scarring
Active skin infection
Allergy to one of product ingredients or to lidocaine
Excessive steroid use within the last year
Adverse reaction to previous injectables
Important considerations for consultation (PLLA).
- Ensure pt fully understands how PLLA works
- Does not give immediate results, except for few days following treatment
- Weeks to months for full effects
- Obtain signed consent
- Clinical photographs (pre- and post-)
- Complications education
What is the craniofacial protocol for clinical photographing?
Straight AP
True lateral
45 oblique degree
Which areas of the face is PLLA treatment effective for?
Malar area Eyebrow (deep injection in contact of bone) Cheeks (pre-auricular area) Prejowl sulcus Chin area along the mandibular border Under the DAO muscle Mental fold
Which areas of the face should PLLA not be injected in?
Thin skin areas such as eyelids or crows feet
Hyperdynamic areas such as DAO, commissures, peri-oral area and peri-orbital area
Lips for volume
Forehead lines to avoid collagen hyper-stimulation due to lack of fat
Superior white lip to avoid collagen hyper stimulation due to lack of fat
Which areas of the face should special care be taken for when injection PLLA?
Temples (vessels, temporalis artery)
Tear trough
Nasolabial folds (arteries, reflux needed, insect slowly)
Pre-auricular area (presence of parotid gland, reflux needed)
Medio jugal fold
What is the product composition of SCULPTRA (PLLA)?
PLLA powder - 150mg
Carboxymethylcellulose
Non-pyrogenic material
What other required instruments for PLLA?
Sterile water for injection
Sterile syringe single-needle 5 or 10ml and 1 to 3ml
Sterile needles 25G (long or short), 26G (short)
Antiseptic
Lidocaine 1% or 2% with or without epinephrine
Mepivacaine
How is PLLA product reconstituted?
Product diluted - 150mg vial of PLLA is diluted in 9mls water for injection
Product hydration - Leave product to stand at room temperature for at least 24 hours
Addition of local anaesthetic - add 2mls of 1 or 2% lidocaine or mepivacaine, roll until a homogenous translucid suspension is obtained
How is PLLA prepared for injection?
Injection amount and interval schedule:
- Max 1 vial per side of face per session
- At least 4 weeks between treatments for young patients and 6 for old patients
Preparation of injection syringes:
- Clean rubber stopper
- Use a second 18G needle to withdraw the appropriate amount of suspension into 1 or 3 ml syringe
- Once ready to inject change needle to 25G or 26G
- Discard each needle/syringe with product after each patient
What is the PLLA injection technique?
Inject supraperiosteal (from deep tissue to supraperiosteal area)
Use fanning or cross hatching as per anatomical area with maximum of 0.3ml/cm2
In SC areas such as deep folds and depressions, injections should be parallel to the skin with a maximum of 0.1ml/cm2
PLLA - aftercare?
Massage treated area for 1 to 2 min before continuing to next area
After whole treatment, intensive massage for 5 mins
Pt must massage treated areas for 5 mins BD for 1 week (prevent nodule formation)
Pts can use skin cream to massage skin
Massage method - rotative, bi-digital intra-oral massage
What are the immediate complications of PLLA?
Bruising
Swelling
Erythema
Haematoma
Usually self limiting and will resolve spontaneously within a few days
What are delayed complications of PLLA?
Oedema Non-visible but palpable nodule Visible papules Nodules Granuloma
PLLA complications: Granulomas vs Nodules
Granulomas:
- Suddenly, 6-24 months after injection, at all injected sites at same times
- Growing to size of a bean, with skin discolouration, oedema
- Grow fingerlike intro surrounding tissue
- If untreated, disappear after 1-5 years
- Foreign body granuloma; particles or microspheres are scattered
Nodules:
- 1-2 months after injection, after swelling vanishes, single nodules, close to facial muscles, particularly in the lip
- Remain the size of a lentil or pea
- Well confined to fibrosis capsule
- Until absorption (or permanent)
- Particles of microspheres form aggregates
How to prevent papule / nodule formation in PLLA treatment?
- Reconstitute product at least 24 hours before treatment
- Increase dilution with 9mls
- Inject appropriate areas
- Do not inject too superficially, intradermally or in hyperdynamic areas
- Do not overcorrect
- Do not treat patients with autoimmune diseases or patients prone to diseases requiring interferon therapy
- Always massage after injection
What is treatment of non-inflammatory nodules?
- Could wait for spontaneous resolution (reassure, wait and follow up)
- Vigorous massage
- Treat areas in between with hyaluronic acid fillers to even out surface
- Invasive treatment: Use small gauge needle (26G or 30G) with saline or lidocaine to break up the nodule
- If fails to response, inject intralesional corticosteroids inside lesion (triamcinolone acetonide). Injection should not exceed 0.1ml per cm nodule for 1-3 times depending on size and response. Should be separated by 3 weeks. If no response 2-4 weeks increase volume of injection.
What is treatment of granulomas?
- First line: Doxycycline or Minocycline for 6 weeks, can be combined with intralesional injection of cortiocosteroids
- Second line: Intralesional injection of corticosteroids
- 5FU +/- intralesional injection of corticosteroids
- Third line: Immunomodulotherapy + oral steroids 7-10 days
- Very rare cases: surgical excision
What are the properties of fat that make is an ideal choice for soft tissue augmentation?
- Biocompatible
- Autologous - readily available, less chances of rejection
- Remains stable once grafted
- Non-toxic
- Resistant to infection once grafted
- Totally integrates at recipient site and no longer detectable
- Natural
- Can be placed in all layers (superficial and deep) in face, hands and other parts of body