L10: Bone stem cells part 2

Question 1

what type of bone do the two bone regeneration pathways involve

Answer 1

intramembranous: e.g calvaria
endochondrial: axial/appendicular skeleton

Question 2

injuries

Answer 2

Fractures & Bone Healing
Endochondral ossification is recapitulated during fracture healing (especially in long bones).

Temporary cartilage intermediate is formed → replaced by bone.

Therapy considerations:

Recruit/activate correct progenitor cells.

Decide which type of bone to regenerate (e.g., cortical vs. trabecular).

😷 Maxillofacial Injury
Healing follows intramembranous ossification (like skull bones).

Distraction osteogenesis: A process to lengthen bones (e.g., jaw).

Can involve intramembranous or endochondral ossification.

No exogenous cells—relies on resident bone cells.

🧬 Cartilage Regeneration
Two types of cartilage:

Growth plate cartilage:

Crucial for long bone growth during development.

Defects in growth plate chondrocytes can cause short stature.

Articular cartilage:

Lines joints for lubrication and smooth movement.

Chondrocyte fate decisions:

Some remain in joints for lubrication.

Others contribute to growth plate during development.

🦠 Osteoarthritis & Cartilage Repair
Cartilage does not regenerate well—unlike bone.

Osteoarthritis involves degeneration of articular cartilage.

Current therapies focus on symptom relief and experimental regenerative strategies (e.g., cell-based therapies or tissue engineering).

Question 3

stem cell sources for therapy

Answer 3

cells from developing organs- fetal stem cells
- limited to date
- neural stem cells, primordinal germ cells (gonadal ridge), pancretic islet cells, fetal liver, cord blood

adult stem cells
embryonic stem cells-icm of blastocust, pluripotent, expandable, high frequency
ipsc