Skeletal Healing/Osteoimmunology (Lecture 6) Flashcards
Fracture healing process
• Intramembranous bone from the ____
– joins the fractured ends together
• Endochondral bone formation
– forms a ____ which stabilizes fracture healing
– movement of bone during fracture healing would otherwise interfere with union of fractured bone
periosteum
callus
Endochondral Bone Formation in Fracture Repair
Initial Response
- ____ formation/Fibrin clot
- Activation of BMSC/Recognition Response
first event that occurs is inflammation; a formation of a ____
inflammation is important in fracture healing because it activates the ____; the SC come from the ____; they migrate from the bone and take care of both the intramem and endochondral healing
hematoma
hematoma
SC
periosteum
Fracture callus
a stabilizing callus that prevents ____ during the healing process
movement
Stages of Fracture Repair
Initial Injury:
____
____ recruitment
Periosteal Response:
Vascular In-growth
____ bone formation
Primary Bone Formation:
Cartilage Formation Osteoclast removal cartilage
____
____ bone formed
Secondary Bone Formation:
Osteoclast ____
Coupled Osteoblast Establishment of ____ Remodeling to original form
inflammation
sc
intramembranous
vascularization
endochondral
remodeling
marrow
Fracture healing occurs in stages
- ____
- Inflammation
- Recruitment of ____
- Cartilage formation
- Cartilage resorption/vascularization
- Bone formation
- Bone remodeling and removal to reduce excess bone
____ for endochondral
____ for intramembranous
fracture
SC
OB
chondrocytes
Fracture healing as a post-natal developmental process: molecular, spatial, and temporal aspects of its regulation
this is a similar mechanism to what you would see in a ____ (proliferating, hypertrophic, etc.)
growth plate
The Initial Hematoma Releases GF to Stimlate the Repair Process
first step: hematoma/inflammation; kicks off the repair by releasing GF from ____ (a rich resource of GF)
PDGF-BB (specific to ____), FGF-2, VEGF, IGF-1, TGF-beta
____ and ____ also release GF; MSC release factors important for ____ that is important for inducing the epithelium
platelets platelets WBC MSC vascularization
Fracture Repair and SC
MSC form fat, bone and muscle tissue; in healing fracture, the MSC migrate from the ____: away from bone: form ____, towards bone: ____
____ OF CELL determines what it will become
periosteum
chondrocytes
osteoblasts
spatial location
Endochondral Bone Formation in Fracture Repair
Proliferative response Mesenchymal Stem Cells
____ Cells
Tissue Formation Chondrocytes – cartilage
Osteoblasts – ____ bone
Endochondral ossification
Cartilage calcification
Invasion of blood vessels
Removal of cartilage and replacement by bone
formation of a hard ____
the initial cartilage calcifies > hard callus, which is ____; gets invaded by BV, contains OPC > stimulated into osteoclasts > removal of cartilage > ____ are released and new cells come in which form the calcified bone
endothelial
intramembranous
callus
functionally stable
signals
Endochondral Bone Formation
The first event that occurs is the hematoma and inflammation. This causes platelets to degranulate, and inflammatory cells to migrate
and release ____. This leads to the stimulate of stem cells. They can lead to ____ and ____ bone
formation to repair the bone.
The area of endo bone formation stimulates stem cells to produces chondrocytes that produces cartilage.
The OC and vascularization and stem cells migrate in again which leads to bone formation. This is an anabolic formation of tissue, this
is followed by catabolic prices. The overall reaction is ____ because there is more OC activity than bone formation.
growth factors
endochondral
intramembranous
catabolic
Intramembranous bone formation and remodeling
For intra bone formation, stem cells will
differentiate into ____. This will lead to
____ formation = bone formation.
This new bone gets remodeled
(____).
osteoblasts
anabolic
catabolic
Chondrogenic and Osteogenic TF in Fractures
why do you get SC forming chondrocytes and in another forming OB
the reason is: you have TF that are induced by local signals > when cells migrate from periosteum away from the bone > signals they receive induce these TF > differentiation of chondrocytes > migrate toward bone: ____ and ____ > formation of OB [occurs within the early event of the MSC]; or ____ and ____ for formation of chondrocytes
These transcription factors bind to the ____ region
runx2
osterix
sox9
sox5
promoter
Angiogenesis and Fracture Healing
Angiogenesis plays an important role in bone formation by providing ____ that are needed for formation of osteoid and mineralization of bone.
BV bring cell types with them: the OPC travel through BV; it also brings nutrients, and they are surrounded by a ____ (which are ____) > important when you have a ____ from cartilage to bone
nutrients
pericytes
MSC
transition
Bone healing in extraction sites
Trabecular bone formation occurs in ____ stages of bone healing. Two ways to form woven bone after tooth extraction:
1) Trabecular bone from existing bone surfaces (blue arrows)
- Osteoclast-____
- ____ coupling
2) ____ woven bone with osteoblasts derived from mesenchymal stem cells that migrate into extraction socket (red arrows)
- Osteoclast-____
occurs ____; if you drill a hole in the alveolar bone it won’t heal as quickly as the removal of a tooth
the ____ is loaded with cells that can form bone (mostly MSC-like cells)
early
dependent
osteoclast-osteoblast
de novo
independent
spontaneously
PDL
Osteoimmunology
Interaction between the ____ and bone
immune response
If you look at someones mouth, you can see inflammation but you dont know if it is from the
bone. You can see that the gingiva is the same. But you have no idea what the bone levels
are. You need to ____ to measure the bone height or take an ____. You cannot diagnose just
from ____ at it.
probe
x-ray
looking
• Gingivitis
- Inflammation of the gingiva that is ____
- Does ____ cause periodontal bone loss
• Periodontitis
- Inflammation causes periodontal ____; ____
• Periodontal diseases
- Includes both ____ and ____
reversible not bone loss irreversible gingivitis periodontitis
Pathogenesis of Periodontal Disease
- Stimulated by ____.
- Bacteria stimulate inflammation:
• ____ immune response (e.g. PMNs, macrophages)
• ____ immune response (e.g. lymphocytes) - Immune cells (leukocytes) produce ____ that
initiate and amplify the level of inflammation. - Cytokines stimulate ____ formation.
bacteria innate adaptive cytokines osteoclast
Periodontitis
once barrier is comprimised, the bacteria can cross the epithelium > when bacteria see the cells, ____ are released and leukocytes enter
as the bacteria migrate deeper, it gets closer to bone > ____ is very importnat; when its close to bone > formation of ____ > bone resorption > ____ blocks the repair process of bone
____ blocks the regeneration of bone which should be always followed by resorption
chemokines spatial inflammation osteoclast inflammation inflammation
Phagocytes:
____ and
____ that kill bacteria and secrete
____ which affect other cells to increase inflammation
Dendritic cells: Capture microbes and
____ them to lymphocytes.
Phagocytes are the ____ line of dense against bacteria. Nuetrophils and macrophages produce cytokines that stimulate other inflammatory
cells. The inflammatory cells work in ____, they dont work alone. you need the ____ immune response for the phagocytes to be
effective. The phagocytes dont recognize the bacterial that well, so when the Abs bind to them, the phagocytes recognize them ____.
____ is also necessary. Phagocytes work better when stimulated by cytokines. Macrophages work better when stimulated by ____. This interaction is important is needed in an effective immune response when bacteria keep invading into the gingival
tissue.
macrophages
neutrophils
present
first
networks
adaptive
better
T cell activation
gamma interferon
Adaptive Immunity
• Presentation of antigen by antigen presenting cell
• Antigen presented to ____
• Results in lymphocyte activation
The primary antigen presenting cell is the ____. Other cells are also capable of
presenting antigen including ____ and ____. They present antigen in the lymph node
which leads to the activation of lymphocytes. These two arms of the immune response talk
to each other and make each other more effective.
lymphocytes
dendritic cell
monocytes
B cell
Lymphocytes:
B cells – produce ____ and ____
T cells – kill ____, regulate other ____ and produce ____
antibody cytokines cells lymphocytes cytokines
Bacteria Induce Cytokine Production in Macrophages
Bacteria stimulate macrophages to produce cytokines (____ and ____). This has a big effect on ____ so
macrophages and neutrophils also act on each other.
IL-1 (inflammation)
TNF
neutrophils